Continuity mistake: When Raymond finds Charlie and Susanna making love Charlie runs after him. A moment later we find Susanna soaking peacefully in a hot bathtub, without even nearly enough time to get in. Additionally, when they talk while Charlie is sitting on the side of the tub, wet strands of Susanna's hair appear in front of her shoulder. (00:33:10)
Revealing mistake: On their first stop after leaving Walbrook Charlie and Susanna make love. Raymond comes into their room, Charlie gets mad at him, and when he gets out of bed you get a glimpse of the sheet that prevented skin contact between the two 'lovers'. (00:32:35)
Visible crew/equipment: When Charlie is taking Ray to the bar for his date with Iris, in the mirrored wall behind them you see a lady in a blue shirt motioning for the extras to walk by the camera.
Continuity mistake: When Charlie comes back from Dr. Bruner's office and asks Raymond to get out of the car Susanna's hands are in her lap. When the camera angle changes her arms are up on the back and the side of the car respectively. (00:17:55)
Continuity mistake: Near the end of the movie Raymond gets evaluated by Dr. Marston. When the doctor blames Charlie for kidnapping his brother his hands are on the table. When the camera angle changes to a side shot they are folded in front of his face, holding a pencil, and in the next shot they are down on the table again. Additionally, at the end of the scene a tray with water glasses gets shifted back and forth in alternating shots. (01:55:40)
Continuity mistake: After the opening credits, while the red car's being lowered, the angle changes to a close-up and all the people in the background change positions: A man behind the red car walks around it twice, and 2 people appear from nowhere next to a white car.
Continuity mistake: Back in LA Charlie talks to Dr. Bruner about Raymond's future. Charlie's nonchalantly hanging hair in front is all combed back from the moment he says 'I never called him back'. (01:48:15)
Continuity mistake: As Tom Cruise walks to the Amtrak train with Dustin Hoffman near the end, they stop about 1 pace from the train door, but in the next shot the pair walk about seven paces to the same spot in front of the train door.
Continuity mistake: After the duo stops at a motel with pink neon, Ray starts reciting his riddle about the guy on first base again, which gets Charlie annoyed and he badgers him over it. After their little exchange, Ray is walking up to the side of the car as Charlie opens the door to their room. Ray is standing very close to the car, standing right on the yellow line of the parking space. The camera then suddenly jump cuts to a higher angle and Ray is now several feet back standing in the middle of the next parking space over.
Revealing mistake: While Ray is driving the car, in the next shot of them driving down the road, you see a police car driving very slowly keeping back the traffic behind them.
Answer: Susanna was there as well; Charlie just used the "date" as a reason for the three of them to go down for a drink together. He knew Iris wouldn't show up.