Translation:Be on time to the movie theater tomorrow night.
what is wrong with be on time to the cinema tomorrow evening (or tomorow night)? Neither were accepted. In every other exercise you allow cinema for movie theatre - I had never heard of a movie theatre before I started duolingo - it is not a term that is used in the UK at all.
"Be at the cinema on time tomorrow evening" is a perfect UK English translation and must be accepted. In fact Duo's translation is certainly not king's English but it contains errors. The preposition "to" is just a translation from the French language into French/English.