The calendars shown for the last part of the film are from 1942, except for November, which is from 1941. The progression of calendars goes December 1941, February 1942, April 1942, July 1942, November 1941, and December 1942. This November calendar portrays the second-to-last vs. fourth Thursday Thanksgiving day confusion, started in 1939 by presidential proclamation, and cleared up by congressional legislation in 1941 for the 1942 calendar.
Whilst Jim and Linda are first singing "White Christmas," at the end of the song the fire behind them appears to explode. The intent was to turn down the fire along with the end of the number, to enhance the fade-out. But because the crew member charged with turning the gas valve to the fire was behind the set, he turned the valve the wrong way at first, and when alerted to the mistake, he turned the valve off as originally planned.