At the end of the episode, when Jennifer gets up from the bed to open a window, she's only wearing a nightgown. A second later, when she's seen lifting a window shade, she's wearing a light-weight bathrobe.
At the end of the episode, Jonathan and Jennifer are in bed, he's wearing white pajamas. The next time he's seen, he's wearing a bathrobe, without being seen to have put it on.
A light shines on Eva in the baggage car, then Jonathan's lantern turns on.
All the chairs and tables on the train are standard office style and nothing is bolted down into floor. This is a major factual error as on a train takes and chairs would be fixed to floor for safety reasons, to have them all loose is very dangerous especially in emergency stops.
The top of the train car that Jonathan is running on is different than the actual cars.
There's an obvious stunt double for Robert Wagner during the fight on the train and then at the station.
Jennifer never tells Jonathan whose body is in their cabin.
During the opening credits, scenes and landmarks of Chicago are shown evidently to suggest this show takes place in Chicago. The outside of Wrigley Field is shown, but the on-field baseball shot was clearly Dodger Stadium in Los Angeles.
The conductor didn't ask the Harts why they were in the baggage car when they were being shot at.