When Chinese people speak English, there are some specific mistakes which nearly all of them tend to make, and some specific English words and expressions which they all tend to mis-use or else overuse like mad. Most of the mistakes which the Chinese typically make when speaking English are connected to particular features of the Chinese language, and now that I am learning Chinese I am beginning to understand the reasons behind some of the most frequent mistakes.
Anyway, here are some mistakes and mis-uses which I have encountered again and again in the English spoken by Chinese people, especially university students:
1) This one is a constant: mixing up "he" and "she" (or "him" and "her", "his", and "hers"). This is a mistake which virtually all the Chinese people who can speak English make, even ones who know English very well. The reason is obvious: in Chinese, he and she are both pronounced exactly the same way, in other words "ta" with the first tone. However, they are actually written slightly differently: 他 means "he" and 她 means "she". All the same, in Chinese minds there obviously isn't the idea of distinguishing between he and she while speaking, and this is clearly very difficult to overcome.
2) Getting adjectives and nouns mixed up. How many times have I heard things like "He is a very patience person", "my assignment is very emergency", "the professor is very humour", "Chinese adverts are not very creativity" etc...
3)Mis-using the word "play": the first time a Chinese adult asks you if you want to meet and "play together" some day, it can be a bit disconcerting. Using the word "play" to refer to adults hanging out or going out together is common, and a bit comical at first.
4) Mis-using the word "let": in Chinese there is a single word, 让 （"rang") which means both "let" and "ask", as in "I will ask my friend to come out" (not as in "to ask someone where the station is"). As a result, the Chinese tend to use the word "let" to mean ask, for instance: "I will let my friend to come out with us on tuesday" or "I will let her to do me this favour".
5) The constant overuse of some particular English words, first and foremost "hometown" and "delicious". This is not really a mistake, but it does allow you to spot a Chinese person a mile off. In China the food is never good, it is always "delicious", and no one ever goes back to their village, town or city for the holidays, they always go back to their "hometown". The word hometown is apparently taken by the Chinese to be the translation of the Chinese word 家乡 （jia xiang). Sometimes they even think that the word doesn't only refer to towns or cities, but can also refer to regions or countries, so for instance a Chinese classmate once asked me: "is England your hometown?". The word is so ubiquitous that I even use it myself when talking to Chinese people.
This is just a short list, the first examples which came to my mind, but I'm sure that anyone who has taught English in China would have many more to add.