The really notable one I can think of is the Hannibal TV series, the two main characters are infatuated with each other and as one of them begins to lose track of who he is, they will cross the line so they're both facing the same direction. It's a handful of shots spread over the entire series, but it's really quite brilliant.

Satoshi Kon crosses the line to explain it in Paprika, it's part of an extended dream sequence. There are a bunch of filming jokes and intentional 'mistakes' in Day for Knight, a Truffaut film about filmmaking, my favourite is the director having terrible problems filming with a cat and when you see the final edit of the scene, it's just a different cat.

It's rare to do it on purpose, breaking fundamental film grammar usually just looks like a mistake. You've got to be very good.