AllMovie

An American astronaut believing himself to be the first person ever to set foot on Planet 51 gets the shock of his life in this animated adventure comedy featuring the voices of Dwayne Johnson, Jessica Biel, John Cleese, and Gary Oldman. Captain Charles "Chuck" Baker (voice of Johnson) was on a mission to boldly go where no man had gone before, a remote celestial body dubbed Planet 51. The scientific community had surmised that Planet 51 was uninhabited, so when Captain Baker steps out of his spacecraft to discover a race of tiny green people living in quaint communities reminiscent of 1950s America, he can't quite believe his eyes. Unfortunately, the tiny extraterrestrials suffer from a universal fear that their utopian community will one day be overrun by alien invaders...just like the extra-large astronaut who now stands before them. As General Grawl (voice of Gary Oldman) and Professor Kipple (voice of John Cleese) attempt to capture the peaceful visitor so they can dissect him and learn more about his anatomy, Captain Baker must count on his robot companion, "Rover," and his new friend, Lem, in order to navigate this strange new world and find a way back home before it's too late.