Hi, I am from India. I came across the following sentence in one of the english grammar books authored by an Indian. it’s part of the spotting error questions.
I opted part (3) as error because of the term ‘Common’ but the book says NO ERROR. Please let me know whether the word ‘common’ here is appropriate or not.
The phrase ‘common friends’ is okay; friends common to all/most/many in the group. But ‘go to the pictures’ does not sound acceptable to me. We normally use ‘go to the cinema/film/movie’.
‘She will not only go to the cinema but also meet some of her common friends in the evening’ will be a straight sentence. There is no need to invert the subject and the verb here since the same person is doing two things (going to the cinema and meeting her friends). While using a correlative in a written context we should exercise adequate caution.
(The question does not seem to have been set with due regard to usage and grammar)
I agree with Coolrus that you’d expect ‘we’ here for ‘our common friends’ to sound good. ‘Her common friends’ could bear different meaning. I would mark 3) as an error too.
Placing negative adverbs and adverb phrases at the beginning of a sentence usually takes inversion (your knowledge of that was checked here).
You are correct.
In standard English that would pretty much be an insulting way to describe the friends.
… some of her friends in the evening
would be correct.
common friends of two or more people - the friends they have in common (they are all friends).
common friends of one person - the friends who are vulgar or uncouth.
Examine these two pairs of sentences:
She will go to the cinema. She will meet some of her (common) friends, too, in the evening.
She will not only go to the cinema but also meet some of her (common) friends in the evening.
She will go to the cinema. Some of her (common) friends will go to the cinema, too, in the evening.
Not only will she go to the cinema in the evening, but her friends as well. (Not only will she, but her friends also, go to the cinema in the evening).
You really seem to have a dislike for her friends, Anglophile. 
No, not at all. Perhaps, I didn’t mean the absurd connotation for ‘her common friends’.
It’s not absurd, it’s the common one.