5 minutes into the movie you see a Rambo 6 on the movie theater entrance marquee, an obvious joke based on all the sequels the movie industry keeps producing. There will be a Rambo (6): Last Blood that's in production right now in 2015 reported to be the last in the series. Rambo fights a drug cartel.
The sitcom "My Brother the Alien" is cancelled by Fox before it has even reached the halfway point of its first episode due to instant Nielsen ratings indicating low viewer interest. This is an in-joke referring to Fox's cancellation of Alien Nation (1989) in 1990.
The theater sign with "Rambo 6" on it, as well as quite a bit of other footage is from the original 1988 movie and has been used in every single intro for the TV movies as well as the series episodes. Almost all of the footage from the movie is from the opening scene where Sykes (James Caan) is driving through the city with his partner and the scene that follows.