Revealing mistake: When the leading hitman jumps from the balcony you see him land on a rubber mat.
Continuity mistake: When the Senator is about to be sacrificed, the cloth on her mouth immediately disappears for a split second. (01:29:35)
Factual error: In the first scene where Dr Strange is preparing for surgery he uses improper surgical gowning technique breaking aseptic protocols. Strange puts on a mask after washing his hands, contaminating his clean hands by bringing them in proximity to the non-sterile environment of his face. Surgical masks must be worn before the full washing of hands. Another error is that he inserted his hands all the way through his gown to don gloves. Hands must never leave the sleeves and gloves must be put on with the sleeves still covering.
Continuity mistake: It was briefly stated in the second film that the T-Virus was created by Dr. Ashford to cure his daughter Angela and that the Red and White Queens were based on her. This movie contradicts that by suggesting that Dr. Marcus created the T-Virus to cure his daughter Alicia, and that the Red/White Queens were modeled after her. While the rest of the movie stays true to the continuity of the previous films, this rather obvious ret-con is still a major continuity gaff.
Plot hole: When the group is walking through the jungle for the 2nd time, they have nothing more than their backpacks and a horse to accompany them. Suddenly we see them rowing down a river on a boat and raft. After making peace with the savages, when they have to let a group member go to get medical help, they have been washed ashore as they have been traveling on a single raft since the canoe was damaged by spear attack. How is it that they had a horse and an Indian guide to send away with their injured man? (01:16:55)
Continuity mistake: When Mrs. Otterton is in Chief Bogo's office holding her family photo with both paws, in the wideshots her purse is hanging in the crook of her left arm, but after a brief shot of Judy, when it cuts to Mrs. Otterton's closeup as she tells Bogo about her two beautiful children her purse is gone, then after another brief shot of Judy the purse is back in its place again in the wideshot.
Visible crew/equipment: When Dewey is introduced and has a phone call with Jeffers about the leak, he is packing away files in a briefcase. On his desk there is a pad of paper beneath Dewey's mobile, and the scripted lines for Dewey's side of the phone conversation are handwritten on the top sheet, not being removed from set prior to filming. (00:08:25)
Continuity mistake: The doctor starts out carrying a Holland and Holland "Royal" Double Rifle; but when he and Tarzan pursue the train, the doctor loses his H&H rifle in the leap from a cliff. Lo and behold, after they commandeer the train and disembark, the doctor is inexplicably carrying his H&H Double Rifle again. The H&H is not a common rifle, even today, and his chances of just discovering an exact replacement aboard the train is beyond coincidental.
Character mistake: When Mike and the SAS team leader first meet, the team leader introduces himself as Will Davis, Captain. However at the near end when they say goodbye to each other, Mike addresses him as Lieutenant. (01:07:35 - 01:25:35)
Factual error: The film shows cactus and agave plants in many scenes - those plants were imported from the Americas to Judea 1800 years after Jesus.
Continuity mistake: When April changes into a school girl's outfit to distract Dr. Stockman's assistant, she grabs a miniskirt and ties it around the skirt that she's already wearing. But we never see her take this particular skirt off. It just magically disappears. She is also wearing pantyhose which suddenly changes to over the knee stockings.
Factual error: The villain performs his hit at the beginning of the movie by remotely changing the GPS destination of a cab, so they head to the wrong place and into an ambush. Assuming that neither the cabbie or Pope notice the change on screen, and that his sophisticated software silenced the voice announcement of the course being recalculated, and makes the new place also marked as the old one (it is after all a god-like movie software), the trick is done on on a London black cab, whose drivers are notorious for "The Knowledge", aka being required to learn the entire topografy of the city in one of the most demanding training courses in the world, and not using GPS. It'd be definitely unlikely for the cab driver to be totally unaware, to the point of Pope himself noticing first that they are at the wrong place.
Factual error: When Eakins returns to the house after he swears an oath to the union. You can see a thermostat on the wall behind him. (01:40:00)