Jim Backus and Victor Mature were filming Androcles and the Lion, a film which required them to appear in the full regalia of Roman soldiers. One day, during a break in filming, Mature told Backus, "I have to run an errand. Want to go for a ride with me?" It was too much trouble to change out of their costumes so they didn't. They got into Mature's car, drove off the lot and made a quick trip to a business that Mature owned about a mile away.
On the way back to the studio, Mature insisted they stop off at a neighborhood bar for a quick drink. Backus protested that they were still in costume but Mature said, "Aah, they won't care in this place."
The two men walked in and the bartender stared at them in amazement. After a few seconds, Mature asked him, "What's the matter? Don't you serve servicemen?"