When Tango and Cash escape from the prison, Cash turns to Tango and asks if he stopped "for coffee and a Danish." Tango (Sylvester Stallone) says, "I hate Danish," an in-joke referring to his recent divorce from Danish actress Brigitte Nielsen.
When Brion James was originally hired to play Requin, it was a very small role with only two lines. In an effort to give the character something that would make him stand out, James decided to speak in a cockney accent. Sylvester Stallone loved it, and rewrote the script to give Requin a much bigger role.
The climatic battle in the quarry was shot in a real quarry east of downtown LA, in Irwindale. Every shot in the sequence was shot with a minimum of 11 cameras, as some of the setups were so dangerous, the stunt team were only allowed to do it once.
During the scene where the back of the SUV catches on fire, when filming was over, the fire wouldn't go out, and actors Kurt Russell and Sylvester Stallone were caught in a cross draft. Stallone was so close to the fire that his hair was singed in places.
The production was beset with problems from its very inception. Firstly, the intended star, Patrick Swayze dropped out, then principal photography began without a completed script. As mentioned above, Sylvester Stallone had the original director of photography, Barry Sonnenfeld fired. Then, the director, Andrey Konchalovskiy was fired by producer Jon Peters. The film ultimately went over $20 million over-budget, and had to be completely reedited by Stuart Baird prior to its release.
Director Andrey Konchalovskiy was replaced towards the end of principal photography by Albert Magnoli. In his book of memoirs, Konchalovsky says that the reason he was fired was because he wanted to give the film a more serious tone than the producers wanted, and as such, his relationship with producer Jon Peters became untenable. Konchalovsky however has nothing but praise for Sylvester Stallone, who he states was a constant voice of reason on the set.
The glasses worn by Sylvester Stallone for the early parts of the film are his own and not just a fake prop (he usually wears contact lenses in his films). If you look closely, the glasses indicates he's quite near-sighted on one eye but not so on the other.