 Williams previously worked with Homicide executive producer Barry Levinson on the films Good Morning , Vietnam ( 1987 ) and Toys ( 1992 ) . This led to speculation that Williams took the role on " Bop Gun " as a favor to Levinson , but the actor insisted it was out of admiration for the series itself . A young Jake Gyllenhaal , the son of the episode 's director , makes an appearance as Williams ' son . The episode was the first to feature Chris Tergesen as music coordinator , which resulted in the use of more songs than previous episodes , including " Killer " by Seal and " Feels Like Rain " by Buddy Guy . 
