When leaving the dance club, Catherine and Cash get on her motorcycle. You hear the motorcycle start and rev once, but Catherine's right hand is down by her side, not anywhere near the throttle (or the start button for most bikes).
During the prison escape, on the roof while attempting to jump to the power line, the camera front view has Cash wearing a sleeveless shirt. When camera shot is on the back of them Cash (or rather his stunt double) is wearing a tee shirt with sleeves.
During the raid on Perret's compound, the armored SUV that Tango and Cash are riding in drives through a large explosion, during which time the driver's side front headlight goes out. In subsequent shots, the headlight is fixed and shining bright.
When Tango visits Wyler at Wyler's house, he surprises Wyler, who is taking a plate of spaghetti out of the refrigerator. Wyler is surprised at Tango's appearance, and drops the plate. When Tango looks at the plate on the floor, a fork has appeared on the plate, despite not being there when it was dropped.
During the raid on Perret's compound, Cash is in the stairwell firing an automatic weapon that appears to shoot bullet holes in the wall of the stairwell. The bullet holes appear in different amounts and patterns between shots. Also, Tango has an automatic weapon and fires it right at the lower side of an office desk he has dived to for cover. The muzzle flash is clearly reflected on the side of the desk surface, yet no bullet hole damage occurs to the desk.
After being attacked in his apartment, Cash jumps of the balcony chasing the attacker. When jumping off the balcony he jumps on his back, as if expecting to land on an airbag. In the next scene, he is seen falling on his face and rolling forward as he lands.
When Cash is pushing a garbage can/truck in the prison yard, at the beginning of his escape attempt, the lower leg and foot of someone also pushing it on the far side from the camera can be seen, by the bottom right corner of the can.
At the beginning of the movie when the truck is bearing down on Tango and he fires at the truck, the windshield "spiderwebs", as it should, since it would be safety glass. However, when the two men fly through the windshield after the truck is stopped, there are no bullet holes in it and it is clearly a plate glass windshield (due to how it shatters).
When Tango and Cash attack Perret's compound and they use bulldozers to crash into the building, the ammunition crates inside are nothing more than empty boxes, with no contents and nothing holding them together.