When Michel and Terry speak to one another the evening before the liner's arrival in New York, Michel's scarf pattern changes between shots.
When the sailor takes the photograph of Terry and Michel, their position on the railing changes depending whether the view is from in front (close together, nearly touching) or from behind (about two feet/ 60cm apart).
Toward the end, when Terry is on the sofa talking to Michel, she offers a cigarette to him. He picks it up, puts it in the mouth a little while and takes it out. Next shot, the cigarette is in his mouth.
Michel's grandmother Janou speaks French (and English) with a foreign accent; it is unclear where she's supposed to be from.
An accent that a viewer cannot identify is not a Goof; it is a filmmaker's artistic license.
An accent that a viewer cannot identify is not a Goof; it is a filmmaker's artistic license.
When Terry and Michel are on the ship during the day and they are next to the railing talking and reading their letters, the ocean is moving behind them. Just after the closeup on Terry, she turns and faces the ocean, and the shadow of her head can be seen on the screen that displays the ocean.
When Michel is waiting for Terry on the Empire State Building into the evening, and a thunderstorm breaks out, the same forked lightning strike is seen at least 4 times in the background, always in the identical location.
On the ship, at the railing, before and after disposing of the photographer's film of a compromising photo, shadows of Irene Dunne are visible on the background screen of the ocean: a shadow of her head before the photo incident and her arm as she stretches afterward.