In the opening scene, Tom is lounging on a throne, obviously bored. He yawns and covers his mouth with the front of his hand. Cut to the next shot, and he's now covering his mouth with the back of his hand.
After dancing on the ceiling, Tom is holding and looking at a picture of Anne as he twirls into a chair to sit down. As he approaches the chair, his left arm is bent at a right angle with his hand by his waist; just before he actually sits, there is a cut, and his left arm is extended straight outward.
On the day of the wedding, many of the British flags in the streets are hung upside down. The wider diagonal white stripe of the Union Flag should always be uppermost next to the top of the flagpole.
When Ellen's two suitors have a brawl in the New York bar, the last frames of the scene show the boyfriend facing the camera breaking character and laughing.
When Tom and Jamie are in a taxi, the projected background shows numerous black London taxis, but when their taxi stops, it's an old-fashioned light blue; certainly not a London cab.
When asking the name of the ship they'll be sailing on to England, they were told it's a French ship. The following shot of the liner at sea displays colors of the Italian Line.
When Tom and Ellen are talk about getting married after the royal wedding ends and Tom leaves to look for Ann, behind Ellen can be seen someone at a lower level than she, on the street, waving at the royal entourage. As she and Tom were on the street, the background scene is unlikely.
When Tom and Ellen enter the hotel room, Tom casually lets the door swing shut behind him, but a crew member's hand is seen grabbing the doorknob outside to close the door.
London streets have American fire hydrants. Also the same London bus drives backwards and forwards across the set.
After opening in London, Ellen and John go for a walk, but the buildings are those of a village and the road is a dirt one. When they stop on a bridge to look at the river, there is punting, so it's not the River Thames and London.
Three British characters wear striped ties: Lord John Brindale and Edgar Klinger both have English ties, with the diagonal stripes slanting down toward the left. However, Anne's father is wearing an American tie, whose stripes usually slant in the opposite direction.
The morning after the opening, Edgar, the London agent calls Tom and Ellen and asks 'Have you seen the dailies?' which is an American expression.