Sir Alfred Hitchcock, following his usual practice, bid for the movie rights to Winston Graham's novel anonymously, so as to keep the price down. However, in this instance, the scheme backfired; the anonymity of the purchaser made Graham suspicious, although he regarded the amount of money on offer as extremely generous. He instructed his agent to ask for twice as much. Hitchcock agreed, on condition that the deal be closed immediately. When Graham discovered who it was who had bought the rights, he said he would have given them away free for the honor of having one of his stories filmed by Alfred Hitchcock.

Whenever Marnie sees the color red, she reacts with hysteria. However, when she comes back to the Rutland house from the hunt and comes down the stairs after going up to get the safe keys, the shot shows that the carpet on the staircase is red. Yet she is able to go up and down those stairs the entire time she is in that house without any reaction.

Dialogue in the final scene reveals that Marnie's mother had given up her virginity at 15 to Marnie's father in exchange for a sweater. Just before the film's release the studio had second thoughts about this part, and Alfred Hitchcock agreed to cut the lines. But hundreds of prints had already been made, and rather than incur the cost of reprinting the final reel of each, the studio released them as they were, so there were two versions of the film from the outset.

Edited into Histoire(s) du cinéma: Une histoire seule (1989)