Factual error: It is not possible to be "allergic to all known anaesthetics". Amongst the amide local anesthetics lidocaine, prilocaine, bupivicaine, mepivacaine and dibucaine are naturally occurring substances and if administered without a preservative they cannot trigger an allergic reaction. If Bales is allergic to them, he'd be allergic to the metabolic processes of his own body. They are all powerful local anaesthetics and could easily be used for a radical rhinoplasty such as that required by Bales.
Factual error: When they are driving back home from the holiday cottage you can clearly see an M25 sign in the background. The M25 didn't exist in the 60s.
Factual error: When the Joan Cusack character bolts into the control room with the "Mercenary" cassette, you can here the director counting down to roll the tape. A 3/4" tape being inserted and threaded up in the machine normally takes about 8 to 10 seconds, yet the tape plays when the operator hits the play button.
Factual error: Ronnie Cox is shot in the heart at point blank range by Brigitte Neilsen, and it looks to me like she's using a large caliber handgun. Keeping track of the action of the film tells us that Cox is sitting up in bed chatting to his friends just three days later. What nonsense. Even if he did survive (unlikely) he'd still be in Post-Op Intensive Care at that stage. He wouldn't be conscious, let alone allowed visitors.
Factual error: Hot Air Balloon's have no lateral control. They fly in the direction the wind is blowing, so it's rather impossible for two hot air balloon's very close to each other to be flying in different directions, let alone fly exactly to the desired locations.
Factual error: In the beginning of the movie when they are in the kitchen, over on the TV you can see an episode of the Price Is Right, but it was Friday evening. The Price Is Right is on in the morning, so it could not have been playing live on the TV at that time of day.
Factual error: In the "Groovy" shed scene, Ash holds a double-barreled shotgun in one hand and saws through the gun barrels with his newly-mounted chainsaw in about 2 seconds flat. He could no more cut through a hardened steel shotgun barrel with a chainsaw than he could cut through a marble counter-top with a butter knife.
Factual error: At the beginning, when Cindy and her friends return from shopping, Cindy's mother asks for her credit card. Cindy hands her several cards and her mother chastises her, saying that she was only supposed to take the Neiman Marcus card. Tucson has never had a Neiman Marcus.
Factual error: When the silver bullets are being cast, the silverware thrown into the melting pot appears to melt instantly, the bullets come fully cooled and hardened out of their mold in seconds, and are already fully formed and polished, straight out of the mold.