* DawsonCasting: Both leads were older than their characters. Amusingly, Hitchcock denied JimmyStewart the part of Thornhill because he thought he was too old for it - so instead he got Cary Grant, who was even older than Stewart.
* HeyItsThatGuy: The Professor is [[TheManFromUNCLE Alexander Waverly]]. Leonard is [[MissionImpossible Rollin Hand]]. Roger's lawyer is [[Series/GetSmart The Chief of CONTROL]].
* ImageSource: This film provides the page image for:
* ThrowItIn: An unintentional one. When Eve [[spoiler: shoots Roger in the restaurant with the blanks]], a child actor covers his ears before the gunshot happens. The take was still used, since aside from this, it was the best take.
* WhatCouldHaveBeen: While the film was still in the early scripting stage, a scene taking place at an assembly line in Detroit was envisioned, where the camera would follow two men as they talked while a car was built behind them piece by piece...and at the end, one of the characters would open a door of the now-finished car and a corpse would fall out!
* WorkingTitle: ''The Man in Lincoln's Nose''.