Revealing mistake: When Dwight is falling down the stairs, you can easily tell that it's a (much older) stuntman.
Visible crew/equipment: The demolition crew can be seen on the driver's side window when Sonny Chiba and Brigitte Nielson's characters are fleeing the scene of a blown up car. The shot has Robert Davi's character chasing after them and then hearing the explosion behind him. You can see a crew person sitting and about four others kneeling, trying to evade cameras. This happens in scene 6 at 52.01 minutes into the movie. (00:52:00)
Other mistake: In the exterior shot of the Grandeur Hotel, it's a poorly made building prop and its name is misspelled "GRANEDUR." (00:18:00)
Continuity mistake: Alex's hands are bloody after her hunt then they're clean then bloody before becoming clean again.
Revealing mistake: During the final fight, Takeda is chained up between two ninja, and Kinjo orders them to kill him. One of them raises his sword, but is shot by Takedas wife. As the arrow hits, the film noticably "jumps", as the actor is replaced by another with an arrow attached to his throat. Not only does his position (especially his head) slightly change in an instant, but his suit also suddenly becomes a lot darker, and a crease appears in his hood.
Continuity mistake: The Black Scorpion's boots constantly change from heeled to flats.
Continuity mistake: When the cruise ship is overrun by pirates, one of them being pursued by Indy jumps down the stairs fine, but when Indy does it he fails and his hat comes off to the left of the staircase far from his reach. When the shot changes its back on his head.
Factual error: The cap badge worn by Captain Halliday of the RAMC is the Queen's crown version, which didn't come in to use until the 1950's. It is also made of brass, when it should be in a bronzed finish for officers.
Character mistake: When Bonnie cuffs her first arrest she mistakenly cuffs the guy in front instead of cuffing his hands behind his back.