Factual error: The KGB agent hunting Jonathan is carrying a Spanish Campo-Giro pistol. There's no way a KGB agent would carry a foreign sidearm in a Soviet Bloc country, especially one that was phased out of service in the late 1920's.
Revealing mistake: Just before Michael and Ellie get out of his car, a fire extinguisher is seen mounted above the dash. Michael opens the hood and the engine begins smoking. Michael reaches into the car for the extinguisher. You can see through the windshield that he is handed another extinguisher instead of removing the one from its mounted spot. The mounted extinguisher is still visible in its holder. Likely done to preserve pacing so he doesn't have to fumble with the clamps on the mounted one.
Other mistake: Jack glances at the front of the baseball card the Consul gives him, and he says "Hap Ashby, 1963 Angels." He has no idea who that guy from 200 years before is, but the card does not say the year, and he's not a psychic. (00:15:55)
Other mistake: Most of the obvious misses and awkward parts of the action in the opening can be attributed to the fact that it is revealed a few minutes later being just a drill. However, it does not make sense on any level. The training makes use of live explosives, and at the same time no gunshots are fired but only grenades, with unrealistic trajectories and range. The 'terrorists' don't use their rifles if not to try and bash the good guys on their skulls. That's quite the subpar training, but the top brass are impressed.
Revealing mistake: During the opening assault, notice that the sandbags of the enemy fortifications are more like fluffy pillows; they are squashed under a single person leaning on the bank, and they wobble and nearly fall over when Carrasco himself brushes the hip against them walking by. (00:04:30)
Character mistake: Morgan Hiller's father is named Stewart (according to the story as well as credits). But in one scene when Morgan and his parents are having dinner, Mrs. Hiller calls him (her husband) "David" one time (instead of Stewart).
Audio problem: Just after Binx shoots Mr. Pyot, Hube says, "Don't touch him!" When Billie Jean bends down, the camera cuts to Hube who reaches for the phone saying, "I'm calling the police," but his lips don't move. (00:18:40)
Continuity mistake: In the cabin, the survivor and Howe hear an explosion, and the survivor goes out to investigate. He pulls up a board and unlocks the door, and only closes it after him. When the girl comes up from the basement, the door is closed, locked, and barricaded.
Continuity mistake: When the men posing as painters rip off the drug dealers, they place a scaffolding plank to cross to the other building, which they remove from the windows and it falls onto the street. When Chuck Norris enters the apartment it reappears.
Audio problem: When Quatermain and Jesse are fleeing in a stolen truck, they are being chased by people in other vehicles. Even though all the streets are dirt, there are numerous times when the tires of all the vehicles squeal.