Legal Question in Civil Litigation in California

Why do you think a Coca-Cola is $6? Some theaters have recently lowered their prices.

With very rare exceptions, movie theaters are private property. As long as they don't discriminate on the basis of race, religion, gender, etc., they can impose whatever restrictions they want on admission. Forbidding customers to bring food or drinks into the theater is perfectly legal.

Movie tickets are a license to enter private property on the terms and conditions allowed by the owner of the private property. You can make a case that if prohibitions against bringing food and drink into the theater are not stated at the time the license is sold, by signage at least, then they are not enforceable. Realistically, though, they're not going to let you in with the drink and your damages amount to the price of the ticket. So IF they didn't have signs, and IF they didn't print on the ticket "subject to . . ." and you have the time to sit in Small Claims Court for a day for $11, go for it.