Continuity mistake: When Cheech and Chong come into the courtroom, the judge takes off her glasses and holds them. When it cuts, she isn't holding them anymore. (00:18:30)
Continuity mistake: When Cheech and Chong get to the courtroom, there are two pencils on their table. When Chong falls to the floor, no pencils are to be seen. (00:18:35)
Continuity mistake: When Cheech says "He's right man, these are lame" to Curtis, one of the band members is standing behind Curtis. When it cuts to a closeup of Curtis, the guy is gone. (00:21:25)
Continuity mistake: When Chong is on the phone with Cheech and about to go outside you can see a man in a white hat dancing by himself. When it cuts the same man is dancing with a woman. (00:31:00)
Continuity mistake: When Curtis is talking to Cheech about his car and says "you got a taste of soul", Cheech is standing with both his hands in his pockets. When it cuts, Cheech suddenly has a hand scratching his chin. (00:34:25)
Continuity mistake: When the band is done playing, sparks shoot out of Cheech's guitar and the guitar is burning. When it cuts, the guitar isn't burning anymore, then it is burning again. (01:17:35)
Continuity mistake: When Cheech stops to pick up Chong, the driver's window is down. A moment later, it's up.
Continuity mistake: The drum kit is a Ludwig amber Vistalite (see Keith Moon, who had a clear one, and Karen Carpenter, a blue one, neither had bottom heads) like John Bonham played in the Song Remains the same. The drum head on the kick drum in the back seat is on and off in the same scene repeatedly. They're a pain to remove, so it's physically impossible to do so and replace in the same conversation.
Answer: The lead singer is Rick Wilder. The band is credited as "Berlin Brats" (The Groups). The song is called "Psychotic", or sometimes listed as " (I'm) Psychotic", but it seems the middle part was cut out for the film or maybe arranged differently for the film.
Bishop73