Continuity mistake: Keep an eye on the letter that Cary Grant has with all of the names of the potential theft victims. 1) The way it is folded changes from 3 folds to 2 and from up to sideways. 2) The suite numbers are wrong , as seen when CG goes to Grace Kelly's, and it is different from the list.
Continuity mistake: When Grace Kelly says goodnight to Cary Grant and kisses him, she is not tanned. The next morning when they meet again, to go for a swim, she has a sun tan worthy of several weeks worth of sun bathing on the French Riviera. (Or it's bad colour correction on the print). (00:40:00)
Continuity mistake: Robie is wearing a kerchief around his neck. The knot on the kerchief keeps moving.
Revealing mistake: Foussard is killed and his body dropped off the cliff into the sea. There is a close-up shot of his head and torso, facing upward, that is supposed to be underwater. However, the actor is obviously not in water. His hair, that should be floating loosely around his head never moves and appears to be held in an outward position by stiff hair gel. Some type of "special effect" filter is layered over the entire shot to simulate water rippling over the corpse.
Continuity mistake: After the flower market scene. Mr. Houston and Cary Grant are at his hillside villa drinking wine outside the porch area. Cary tells Houston to bring the wine. Houston does not pick up the bottle. As they are walking to the table you can briefly see the table and there is no ice bucket beside the table. When the camera changes there is now an ice bucket beside the table with the bottle of wine in it. (00:27:10 - 00:27:45)
Continuity mistake: Danielle is lying on the float then goes to sit up. The first lower camera shot shows her left leg bending behind her other knee. The high camera angle change shows both of her legs fully extended.
Continuity mistake: When Cary walks into the office at the restaurant of his friend there is a clipboard hanging on the wall of glass. It disappears near the last scene in the office. No one leaves with it.
Continuity mistake: At the restaurant of his friend, while in the kitchen the waiter with the silver streak in his hair sets down two bottles of wine on the coffee table and turns his body away from them. The labels are facing the office. Moments later when Cary picks up one of the bottles the label is facing into the kitchen. The bottle only has one label, as shown when it is thrown to the dishwasher and he catches it then turns the bottle.
Continuity mistake: When Cary walks into the office at the restaurant of his friend there is a brown wooden box on the desk near the lamp. When the restaurant owner comes into the office the box is silver and then changes back to a brown wooden box in the next shot.
Revealing mistake: When Cary walks into the office of the restaurant of his friend, the egg is thrown from Cary's left yet the camera/Cary only looks at the people to his right in the kitchen.
Revealing mistake: When Cary Grant walks into the office of the restaurant of his friend the kitchen has the center island to the right of the dishes tray, right of the light, and right of Cary's view to the dishwasher. There is a single row of dark tiles between the island and the cooks in blue. Later when the dishwasher turns and walks toward Cary the center island has been moved to the left. It is left of the dish tray, left of the light and is now showing three rows of dark tiles between the island and the cooks in blue.