Non-native pronunciations of English

Non-native speakers of the English language tend to carry the intonation, accent or pronunciation from their mother tongue into their English speech.

Grammar differences (e.g. the lack of tense, number, gender etc.) in different languages often lead to grammatical mistakes that are tell-tale signs of the origin. Sometimes non-verbal body language also gives away the origin of the speaker.

Another factor is how the English language is taught to young school children. The pronunciation students use will be affected by that used by their teachers. So there may be distinctive features of pronunciation in those from a particular country, such as India, Hong Kong, Malaysia, etc.

Foreign accents in alphabetical order:

Cantonese (Hong Kong Chinese):

many differences in pronunciation due to the large differences in the sounds used by English and Chinese language, and from the teachers
'r', read as 'l' sound. (opposite of Japanese accent)
'v', read as 'w' sound.
'wh', read as 'w' sound.
'th', read as 'd' sound.
Differences in ending sounds.
Often drop articles like "the" and "a"
Difficulty with verb tenses and plurals in general, as they have no direct equivalence in Chinese grammar.
Confusion of 'he', 'she', and sometimes 'it', as all have the same pronunciation in Chinese.
tendency to raise their voice unknowingly probably due to high noise pollution in Hong Kong.
trouble with numbers larger than ten thousand, in the Chinese language, ten thousand is read as one myriad, 100 thousand as 10 myriad, one million as 100 myriad etc. Chinese speakers often pause before saying big numbers because of the mental conversion taking place in the head.

East Asia (including Vietnamese, Chinese):

Due to the syllabic nature of their native languages, East Asians tend to drop or amplify the ending sound of English words, e.g. "an", "ant", & "and" sound the same.
When raising the tone at the end of a question "You did what?", often the last syllable is lengthened and sounds almost like it is being sung.

Farsi (Persian, Iranian):

I't hard to differentiate Persians since they have really no difficulty pronouncing special sounds (excluded from the English alphabet) like ;

/x/ (like the Spanish: "Juan"), /jh/ (like the French: "Jack"), /ch/ (like the English "child"), /z/ (like "zoo"), /sh/ (like "ship). They have a equivalent consonant for all these phonemes in their alphabet.

Persians tend to have some difficulties, when learning English, to pronounce "th"; both as thing and this, which of course sounds like "ting" and "dis". Also /w/ like the word walk, can sound like "vak".
Persian can sound very melodic with many variations. It's quite different from the Arabic language, contrary to what one might expect at first.
They usually "drag" on the last vowel in fairly long words, while the first is "stressed"; the country Andorra might sound like "ahndoraaaa"
they can trill their R:s if they want to.
It can sometimes sound like as if Persians where pronouncing the first word in some names with "capital letters" (like they are written), names like "Stockholm" or "Bronx" can sound like "EStockholm" or "BEronks".

Finnish:

Due to Finnish always stressing the first syllable, English words accented on the second syllable are often misstressed. "VOcaPUlary".
P and B confused (in Finnish 'p' is pronounced almost the same as 'b').

Difficulty with 'z', pronounced as 's'.

German:

'th', pronounced as 's' or 'z'. (German lacks both [T] and [D].)
's' sometimes also pronounced as 'z'.
'd' , 'g' or 'b' at the end of a word may be pronounced as 't', 'ck' or 'p'.
German doesn't distinguish between adjectives and adverbs, so Germans often drop '-ly' from adverbs.
Use of [ö] for English syllabic [r].

Hebrew:

Hebrew uses a palatalized ("soft") /l'/, whereas English uses a non-palatalized ("hard") /l/
Hebrew has only 5 vowels and generally does not use diphthongs (except for foreign borrowings); Hebrew speakers may therefore mispronounce some of the English vowels.
Hebrew speakers may sometimes gesture or raise their voice in a way which native English speakers may find excessive, although it is considered perfectly normal in Israel.

The Indian Subcontinent:

Fast speech tempo with choppy syllables.
Questions worded like statements. Detected by native speakers because of stress on verb in case of questions.
Using 'ing': Instead of "He has a car", "He is having a car".
English alveolars are perceived by many native Indic and Dravidian language speakers as allophones of retroflex consonants, when Subcontinental dental phonemes are in fact more appropriate equivalents to the English alveolars. This leads to the "hollow" pronunciation of English by many Asian Indians.
they shook their head sideway as they speak as if they are saying no-no-no even when they say yes-yes-yes.

Irish:

Words are pronounced in a rhotic fashion - that is, the 'r' sound is almost always pronounced, even where an English speaker with a Received Pronunciation accent would silence the letter, e.g. car, father.
The 'th' sound as in 'theme' is commonly rendered as the 't' sound in 'team'. As can be seen, this may lead to ambiguity.
In Reported Speech, the reported clause is often preserved in its direct form, e.g. 'John asked me to buy a loaf of bread' becomes 'John asked me would you buy a loaf of bread'.
Some older people pronounce the 'v' sound in 'video' as 'w' in 'witch.' This is because neither letter is native to the Irish language, and 'v' was first accepted as a translation for both in loan words. The English 'w' sound (as in washing) is associated with the vocative lenition 'h' in Irish. That is, where h follows some letters like b, the sound changes: bh sounds like 'v'. Speakers subconsiously try and remove this h, causing the difference.

Italian:

Tendency to add soft vowel sounds to English words that end in consonants, e.g. "I liker the houser" or "I eater chocolate". This arises from the fact that most Italian words end in vowels, which naturally regulates the patterns of speech, so when Italians speak English they import the speech patterns and try to make English words fit by adding extra syllables in the form of soft vowels.
Tendency to say "dee" instead of "the".
Tendency to lengthen the short "ate" sound in words like "chocolate" (i.e. pronounced chocolut by native speakers) to the "ate" sound in "late".

Japanese:

trouble with 'l', read as 'r' sound. (opposite of Cantonese accent)
Might use /fu/ and /hu/ interchangeably as both are the same sound in Japanese. (For instance, "who" might be pronounced as "foo".)
Similar to Spanish in the lacking of the /v/ sound. It now has two accepted pronunciations, /b/ and /wh/ (i.e. Video becomes bideo or whideo).
tend to insert vowels particularly at the end of a words ending in a consonant, e.g. sound as soundo.
often drop articles like "the" and "a"
don't distinguish between singular and plural
trouble with numbers larger than ten thousand, in the Japanese language, ten thousand is read as one myriad, 100 thousand as 10 myriad, one million as 100 myriad etc. Japanese speakers often pause before saying big numbers because of the mental conversion taking place in the head.
often nod their head when they speak as if they are bowing repeatedly.

Korean:

Difficulty distinguishing 'r' and 'l' sounds.
'v' is pronounced 'b'. 'Video' becomes 'bideo'.
Unable to distinguish 'j' and 'z'. The names 'Jack' and 'Zack' sound exactly the same to most Koreans.
Tendency to add schwa sounds to words ending with consonants.
Short 'a' and short 'e' vowel sounds are pronounced identically.
Short 'o' sounds are lengthened.
Short 'i' sounds are lengthened.

Mandarin Chinese:

Trouble with final 'm' sound, as 'm' does not occur at the end of a syllable in Mandarin pronunciation, e.g. "time" read as "tine" or "timo".
Trouble with two 'th' sounds (θ and ð), as the dental sound does not occur in Mandarin pronunciation, e.g. "this" read as "zis".
Voiced sounds pronounced as their unvoiced counterparts, eg: "duck" for "dog", "root" for "rude". Mandarin does not distinguish /p/ vs. /b/, /t/ vs. /d/, /k/ vs. /g/, etc. (these letters represent aspirated pairs, not voiced pairs, in pinyin)
Confusion of 'he', 'she', and sometimes 'it', as all have the same pronunciation in Mandarin Chinese.
Often drop articles like "the" and "a"
Difficulty with verb tenses and plurals in general, as they have no direct equivalence in Mandarin grammar.
trouble with numbers larger than ten thousand. In the Chinese language, ten thousand is read as one myriad, 100 thousand as 10 myriad, one million as 100 myriad etc. (See Chinese numerals) Chinese speakers often pause before saying big numbers because of the mental conversion taking place in the head.

Philippines

tend to pronounce /f/ as /p/
often use "he" for females.

Polish:

Trouble with 'th', pronounced as 'd', 't' or - less commonly - 'v', 'f'. (Polish lacks both [T] and [D].) Examples: think --> fink, the --> de.
There also existed an "old school" of pronouncing th as 's' or 'z', like brother --> "brozzer", smith --> "smiss".
Voiced stops ('d' , 'g', 'b' or 'v') at the end of a word or before voiceless stops may become voiceless ('t', 'k', 'p' or 'f'). Examples: Paddington --> "paddinkton".
Trouble differentiating similar vowels like /i:/ and /I/ or /E/ and /{/. Example: both "man" and "men" are pronounced /mEn/.
A few commonly used false friends, most prominently "actually" with intended meaning of "at present".
Generally all sounds are very audible: The Beatles --> /dE bitEls/

Russian:

often a palatalized dental /r'/ is used before vowels, which is absent in English.
lack of differentiation between /x/ (as in "Jose") and /h/ (as in "hot")

Spanish

Trouble with /Z/ and /dZ/, which don't exist in Spanish.
Pronunciation of /v/ as /b/, as the letter "v" is pronounced /b/ in many Spanish dialects.
If a word begins with /s/ + consonant, adding an /E/ to it: Espanish. #/s/+consonant is not permitted in Spanish.

Swedish:

Sing-songy intonation. Swedes often speak English with a melodic intonation, ending sentences on an up-note, much parodized (the Swedish chef from The Muppet Show is a well known example and a Usenet institution.)
'th' is often pronounced as 'd' or 't'
/ch/ as in child, is often pronounced as /sh/ or "shaield"
Frequently uses the wrong person of verbs. (e.g. "They is") Swedish verbs do not inflect for person.
Trouble with the ending -ed, as the following sentence (from the parody sitcom Soap): "Do you think I'm finished?" (pronounced "Finnish"). Answer: "No, Swedish!"
Difficulty with the R:s (southern parts of Sweden), sounds more like "gh".