The glitching on reset is just an effect that Pico-8 does when you reset a cart. No idea what you managed to do with the switch characters button, I couldn't replicate what you described--got a screenshot? The camera will sometimes pan across the 4 rooms you can go to through the doors, but that's all I can think of :¬S

Really sorry about that! The downloaded version is mainly for PC, while the version here primarily works in browsers like Chrome and Edge. You do need WebGL to run the game here, too.