Cochise can be seen in the end cutscene for Heavy Muscle, despite having not joined the Warriors at that point.
At the end of the mission "Payin' The Cost", Lemmy and Beansie have swapped voices; Beansie says "Man, Virgil's gonna kill us" in Lemmy's voice, and then Lemmy says "This ain't over, Warriors" in Beansie's voice.
During the cinematic before fighting Spider and Tiny in the flashback mission "Roots", Spider and Tiny have swapped voices; Tiny says "End of the line, you little faggots" in Spider's voice, and then Spider says "Yeah, end of the line" in Tiny's voice.
The game/movie are supposedly, according to the movie, supposed to take place sometime in the not-so-distant future. However, in the game, the year is given as 1979, which is the year the movie was released.