Spaceball guards use Calico M100 to impersonate space weapons in the film. Lonestarr (Bill Pullman) and Barf (John Candy) steal two rifles and use them, Barf's running out of ammo in the process. Princess Vespa (Daphne Zuniga) uses Lonestarr's to take out a group of enemy troopers.
Modified TEC-9
Modified TEC-9 machine pistols appear to be the standard issue sidearm for Spaceball officers. They are shown with barrel shrouds and without magazines. They are also never fired or even drawn in the film, so it's possible these are just replicas or toys.
Modified M1 Carbine
The debris from Spaceball One land on the Planet of the Apes, and the two chimps that come to investigate appear to have modified M1 Carbines. (Assuming they're using the same props from Planet of the Apes.