I think "movies" should be accepted as well as "cinema". Cinema is correct but it's not as common/colloquial as "going to the movies" or "movie theater".
This is strange: "On Saturday I shall go to the cinema" is deemed false. Has nobody taught the authors of this course that the correct first person form of "will" is "shall"? I'm quite surprised.
I agree. The correct form - or so I was taught - was I shall, you will, etc.