The telegram that Ted Hanover receives from Jim Hardy on Christmas Eve is dated December 25th.
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 1940, 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.
When Lila gives Linda a lift to Holiday Inn, Linda gets in the car, sits down, and starts to close the door. In the next shot, Linda hops into the car again.
Fred Astaire throws a box of candy over the back of a park bench. It lands by a planter but later disappears only to reappear again.
At one point early in the opening song & dance on stage, Crosby grabs Astaire's jacket from behind -- Astaire stops mid-motion holding his right leg up in the air. The next instant cuts to a different camera view, and Astaire is holding his *left* leg up in the air.
The April calendar preceding Easter Parade clearly has a 31 after the 30th, though April does not have 31 days. A bunny's head hides the digit "1", but the "3" of the "31" is clearly visible.
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.
During the "Easter Parade" number it is clear that the backgrounds are painted and placed behind a few "real" trees and bushes. This is especially noticeable in Hi-Def.
When Jim first plays "White Christmas" with Linda at the inn, he sits down to play a piano. However, there is no piano present on the audio track.
When Jim Hardy plays the bells on the Christmas tree at Holiday Inn, he hits the two bells twice, but in both cases, gets different tones the second time. This happens again, almost identically, when Linda Mason plays the bells on the movie set.
When Linda Mason first arrives at Holiday Inn, the scene opens with Jim nailing the Holiday Inn sign to the roof. The soundtrack is off and the sound of the hammer hitting the nail is heard on the backswing, instead of when the hammer hits the nail. The rest of the soundtrack, however, is correctly synced.