Planet 51 has an intriguing premise, promising advance clips, and acid-piddling dog straight out of Alien. But none of that can save a rambling movie that's never quite sure where it's going.
Planet 51's tragedy is that it could have been a decent movie. It starts off with a neat premise: on a distant planet, there is an alien civilization that strongly resembles 1950s Americas — right down to everyone speaking English and grooving to The Chordettes. They even have a love for alien invasion movies, and, through a remarkable stroke of coincidence, the scifi franchise du jour is titled Humaniacs and features a monster that looks like an astronaut. Into this world plunges Captain Chuck Baxter, a middling US astronaut who has been sent to explore the planet (which NASA mistakenly believed was uninhabited) and suddenly finds that, on this world, he is the alien. Naturally chaos ensues. The movie also has some endearing and well-animated characters, especially in rock-craving robot Rover, and a Xenomorph-shaped dog that pees acid. The early clips promised a fun, if light, movie filled with cute science fiction references.