戲院責任-誤入女廁?

There are several issues.

First, it is not illegal per se to enter toilets of opposite sex. To determine if the entering is illegal or not, your intent matters. While the police was called in the situation, it did not sound like you have been arrested or charged. So it is likely that it is just an incident on file with the police.

Second, while the theatre may have some responsibilities in this matter, to successfully go after the theatre, you must be able to prove your injuries caused by the theatre.

Bottom line - while you can potential go after the theatre, your circumstance determines your chance of success.

廁所門口有分男女廁， 光只是進入， 應沒太嚴重， 而是你進去後做什麼吧，
營業的戲院能暗到你看不清楚？ 編吧， 看有法官認同你。

調監視器證明吧。
那是有人看到你當時行為，所以報警， 你找證明清白證據吧