Amanda and Jean-Marc climb into a cab in full daylight, but by the time they've reached their destination a few miles away, it is completely dark.
When Amanda jogs out of the theater, she passes some of the same stores twice.
Amanda's hands when she talks to Jean-Marc for the first time, then later at the Chinese restaurant, change positions constantly.
After the Chinese toast, Jean-Marc drops the napkin from his mouth in the reverse shot but still has it to his lips in the next front shot.
In the opening board room scene, Jean-Marc takes his hand out of his pants twice to shake hands with the man next to him.
A copy of "Variety" has editorial copy on the back page. In reality, the back page of this publication always features ads.
Many of the numbers are accompanied by a full orchestra. No Off-Broadway show could bear such an expense. Of course, "invisible" orchestras were standard for Golden Age-era musicals.
Although the revue is supposed to be taking place in a theater-in-the-round, most of the action actually takes place on a thrust stage with no rear seating and is staged for traditional theater where the audience sits in the front (a proscenium layout).
Obvious rear-screen projection in the medium shots of Amanda and Jean-Marc on the street trying to get a taxi.
Obvious stand-in for Monroe when the camera cuts behind her to Montand during the dinner at the Chinese restaurant.
Although the story takes place in contemporary 1960 New York City, the taxicab prominently featured is a 1947 DeSoto, which was typical of the Post-WWII era, but long since retired by 1960. Likely, the taxi is a TCF studio prop left over from an earlier era.
The "Let's Make Love" show itself has no unifying theme or story.