Mr Nobody is a surreal film starring Jared Leto as a man who doesn't want to make choices and therefore lives all the lives he could possibly lead. The viewer and the main character switch between these different lives and realities. There are some impressive cuts to go from one reality to the other.
There was a small continuity joke in a recent 30 rock episode. (Spoilers)
Continuity always needs to be right, but sometimes there are deliberate errors. Of course you need a good motivation to do one of these, but I think it's great when it gets pulled of right. One of my favourite ones happens in the fifth series of Doctor Who, in the episode "Flesh and Stone".