The gun that Caleb picks up in the park and later uses at the demolition site is a Colt Monitor, an improved version of the M1918 Browning Automatic Rifle intended for law enforcement. As seen in this episode, it was more powerful and accurate that the classic Thompson Submachine Gun. Unlike the original M1918 BAR, which is featured in many films and TV shows, this version is not seen so often, but is also used by Woody Harrelson in The Highwaymen (2019).