Way, way too much information on Pac-Man

It wasn't too long after the release of Pac-Man when word began to spread of players occasionally passing straight through a ghost unharmed, seemingly at random. This rumor turned out to be completely true as most die-hard Pac-Man players can attest. If you play the game long enough, you will eventually see Pac-Man run into one of the ghosts and come out unscathed on the other side—it doesn't happen very often so enjoy it when it does!

Apparently, due to the way the sprites update their location in the Pac-Man maze, there's a very tiny possibility that both sprites can move towards each other and swap locations at the exact same time, allowing the collision detection to never fire. Pretty amazing. And that's just one tit-bit of information about Pac-Man you can find at The Pac-Man Dossier. A simple web page documenting just about everything about this arcade classic.