When Doolittle is floating through space after the explosion, a piece of debris which floats by him is marked "toilet tank thx 138" - a reference to George Lucas' first film See more...
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Factual error: In the scene right after pinback shoots the beach-ball alien, we see the Dark Star space craft cruising past a planet with a sun in the background. You can see a reflection on the planet which is coming from the space craft. I'm sorry, but usually ships in space are not large enough to reflect off a planet, especially to the degree this one does.