If I press and hold a directional key (wasd), and then pause the game with escape, then let go of the directional key, then unpause the game, my character walks in that direction perpetually until I repeat the process without letting go of the key. I have also had a similar thing happen with the mouse but wasn't really able to figure out what caused it.
I'd imagine you're storing values when the game is paused, and then playing them back once the game is unpaused. Good luck and thanks for the game! Found it from Charborg.