The Grass Is Greener

It originally was intended by director Stanley Donen that Cary Grant would play the part of "Delacro", the American tourist, whilst Rex Harrison and his real-life wife Kay Kendall were cast as "Victor Rhyall" and "Hattie", respectively. But Kendall died soon after completing an earlier Donen film, Once More, with Feeling! (1960), and Harrison dropped out of the film because of this. Grant agreed to play Victor instead of Delacro, and both Rock Hudson and Charlton Heston were approached about playing the American character. Both refused, and Robert Mitchum was cast quite late in the proceedings, making no fuss at all about taking third billing. Grant often claimed this had saved the film" and praised his performance highly.

When Victor and Charles play billiards, they use straight-rail billiard balls (two white, one red) on a table with pockets (on which 9, 10, or 15 balls, plus a cue ball, are used).

Babies, some of them naked, on a lawn, are shown as if they were the cast and crew. For example, as the camera crew's names are shown, the babies are seen trying to work a camera; the "editor" is a baby tugging on a film strip, and so on.