Revealing mistake: When Cash's stuntman jumps out the window after the bad guy, his feet move out in front of him so that he will land on his back (on an airbag) - cut to next shot and his feet are magically underneath him as he lands and rolls. As (Cash) runs around the street corner it is obviously a stuntman. When Cash runs down the narrow alley he is not wearing a bulletproof vest, but in a following scene he takes one off. (00:07:05)
Revealing mistake: When Tango and Cash hold a bad guy upside down off a roof, Tango has his arms straight out in front of him, elbows locked, parallel to the ground. This would require incredible strength. In the next shot he holds the bad guy properly, held close to his own body with his elbows bent - but Tango appears to be exerting no effort in order to lift the guy at the beginning of this new shot. We can also see the outline of a harness system to hold the bad guy up under the black silk shirt of the bad guy. (01:17:50)
Revealing mistake: When Tango and Cash are getting attacked down the laundry chute, they are tied up above a water tank with a guy holding an electric wire. Their hands are tied to dry cloth which is then tied to the cable. Cloth has no conductivity so there is no complete circuit when their feet are lowered into the water so they wouldn't be getting shocked. The reason they wouldn't be getting shocked is actually explained later in the movie just before they slide down the electric wire.