It goes without saying that watching movies requires a certain suspension of disbelief, since the exchange of entertainment depends on nobody standing up and angrily proclaiming that Han Solo couldn't possibly be in the future when he was just fighting Nazis and looking for religious artefacts in the past.
But there is also the implicit suggestion - and of course, the fundamental appeal to audiences - that somewhere in our world, all of those delightful, entertaining things are happening. After all, horror films wouldn't pack their punch if you didn't come away thinking that saying "Candy Man" in front of the mirror would lead to definite, horrible death.
Easter eggs and in-jokes now complicates matters, as multiple film universes crash together, but usually, the references are played either jokily enough, as in Mel Brooks' infamous love of bending boundaries and the fourth wall, or defined strongly enough, as in Kevin Smith's fetish for mocking Ben Affleck.
Occasionally though, someone is cast in a movie that makes the logic of the timeline, or the existence of a cultural reference point in that universe impossible, confirming that those movie worlds cannot be part of our own reality in a more jarring, overt manner.
The answer, it seems is that some movies are a window into an alternate reality, where some films that we know and love exist, but other confusingly cannot. And fittingly, it starts with a movie that pretended (not very well) to be all about rigid rules, right up until someone wanted to get laid...