Deliberate mistake: When Harry is seen stepping outside of his hotel the evening after he arrives in Paris, behind him is the familiar Eiffel Tower gloriously illuminated against the night sky. Frequent Paris visitors or residents might recognise the hotel as the Plaza Athenee - to see the Eiffel Tower from there you'd need to be looking in the opposite direction from what we're shown.
Something's Gotta Give (2003)
1 deliberate mistake
Directed by: Nancy Meyers
Starring: Keanu Reeves, Jack Nicholson, Diane Keaton, Frances McDormand, Jon Favreau, Amanda Peet
Revealing mistake: Right before Jack Nicholson sees Diane Keaton naked, there are shots of Keaton getting undressed. There is a close up of swollen feet that you can see are obviously not Diane Keaton's. The far shot shows her with smaller feet and legs.
Harry: Oh. Her. She is a major piece of work. Doc, the woman wears turtlenecks in the middle of summer: she's beyond uptight. Almost makes her fun to be around.
Julian Mercer: Uptight. That's funny, I haven't noticed that.
Harry: Try living with her.
Trivia: During the closing credits the song played is "La Vie en Rose" sang by Jack Nicholson.
Answer: When they were trying to see what time it was the morning after they had slept together.