Tonton Streaming Monsters vs. Aliens (2013) S1E30 - The Beast From 20,000 Gallons

When an asteroid is detected heading for Earth, Team Alien is put in charge of the rocket being sent to destroy it. Meanwhile, Dr. C sends B.O.B. to play hide and seek. Unfortunately, he winds up hiding in the fuel being used to power the rocket, and Team Monster must rescue B.O.B. and alter the rocket's trajectory so it'll actually hit its target.