Just to be on the safe side... In the extra credits jam I made a space shooter where when I pressed the <back> arrow it would rotate the spaceship in the opposite direction of its movement...That was essentially the only way to break the speed... Is it okay if I impelent it in this jam or is it considered a violation???

if it was a piece of modular code, and the game you used it in was released, and the game for this contest is a new game and not just the old game remade, then yes, you can reuse it.