Factual error: The picture of Eddie and Teddy on the road with dad, supposedly taken in 1906, shows a Ringling Bros and Barnum & Bailey circus poster. In 1906, the Ringling Brothers circus and the Barnum & Bailey circus were two separate circuses playing in different parts of the country. They did not combine the two shows until 1919. (00:27:00)
Factual error: When Bruce and Patricia are in a lift after being chased by the cars in the garage, the lift rapidly descends but the two people in the lift are seen struggling on the floor when they should just about be on the ceiling due to the speed of the lift's descent.
Factual error: Slater had close to a dozen sticks of dynamite on him. At the very least they should have knocked Winona Ryder down, and made her deaf for a few days.
Factual error: Sean Connery's character is the Provost Marshall for the Presidio, he would not be wearing the MP sleeve placard as he is in the scene at the Officer's Club. He also wouldn't be running around wearing a Field Jacket with the collar up and it unzipped. You wear the jacket correctly or not at all.
Factual error: Shooting at a gas tank with buck shot at 50 meters distance will not make it explode (it likely won't even dent the surface), and lead pellets do not cause sparks when they hit.
Factual error: The movie is set in May 1937, considering that the finale happens during the coronation ball for George VI, May 12 1937. However, in an earlier scene in the hotel lobby (when the matriarch blocks her son's path with her cane) Poirot is reading a copy of The Palestine Post from July 8th of the same year. (00:34:00)
Factual error: Radium Chloride (stated by the doctor to be the ingested poison) does have a slightly luminous glow to it, but absolutely doesn't have the intense shining bright green luminous glow that is shown at the end of the film in Professor Cornell's mug.