The leather jacket James Stewart wore for much of the film is the same one he wore when he was flying missions during World War II.
Joan Fontaine was pregnant during filming. The script, however, luckily indicated that her character wear a man's leather jacket which conveniently also covered her stomach.
A location shooting accident occurred at Newark Metropolitan Airport on Friday 30 April 1948 when a freak wind gust toppled a 15-foot steel tube scaffold with two electricians atop, which fell into a group of 10 actors, production workers and spectators. The injured included stand-ins for James Stewart and Eddie Albert. Three of the injured were detained at St. James Hospital. A Jeep in which Stewart had been riding was damaged. Stewart and Albert, on set, were not hurt. (Via Associated Press report.)