Bender crawls into the torpedo tube feet first, yet when he's fired he comes out head first.
According to Newton's third law the explosions on Bender's body should have affected his speed and direction.
We see nuclear bombs go off in space exhibiting the characteristic mushroom cloud. This is an effect of the atmosphere and gravity and the soil, none of which are present.
Leela states that the ship is the fastest in the universe so they can never catch up with Bender. Speed doesn't work like that you can always speed up with an engine (up to a friction limit) and Bender is powerless.