In the teaser, the crime scene at the motel is Room 1. Later in the episode, one of the local police refers to it as Room 8.
The claim that two different guns must have been used is conjecture at best. An automatic pistol could have fired the high velocity round first, then the lower velocity round, which could have caused the firearm to fail to cycle after the second shot. Just as plausible as two guns.
When Tony is setting up dinner out of his car trunk for Jeanne, she asks him if the scenario is from an old movie; Tony alludes to the fact that it's from Strangers in the Night (1944) with Cary Grant. Cary Grant has never acted in a movie with this title.