None.
Some sci-fi violence and 1950s-style fist fights. Some alien creatures get vaporized and zapped with cheesy energy weapons. A couple of alien monsters meet their ends at the tips of a spear. No blood or gore.
A handful of "damns" and "hells."
The main character starts out as a drunk and drinks alcohol a few times during the film. Aliens drink "space drinks" and seemingly smoke a "space hookah" during a bar scene.
"1950s-drive-in" era appropriate scares. Mostly of the cheesy and laughable variety. Very young children may be frightened in certain scenes but most will find them funny.