All external space scenes and many sets are lifted from one of Don Keith Opper's earlier films, Android (1982).
Critters 4 is the only Critters movie where the Critters are unable to shoot poison darts at their victims.
The footage of the cargo retrieval ship, and docking with the spaceship are from Android (1982) but the footage of Ug's ship at the end are taken from Critters 2: The Main Course (1988).