Continuity mistake: Bing Crosby and Rosemary Clooney are in the bar for a late night glass of milk. Bing puts down the pitcher twice.
Other mistake: In the Christmas party scene all the soldiers are in uniform wearing military boots. Except Bing Crosby, who is in his uniform wearing brown dress shoes, in a war zone. (00:03:00)
Suggested correction: Crosby is wearing dress shoes because he is on stage, entertaining the troops with dancing and singing. It would be hard to do a "soft shoe" tap dance in combat boots. Danny Kaye is wearing boots, but he only does a few simpler dance steps. Crosby is the main entertainer and he would change back into his combat boots once the show was over.
Continuity mistake: During the train club car scene, in the booth next to the foursome (on the left side of the screen) the large menu card leaning against the window continually appears and disappears.
Continuity mistake: When the foursome first arrive at the inn, the general and his granddaughter walk in, both carrying firewood. The granddaughter's bundle suddenly changes shape where one piece of wood is sticking out, then everything is neatly together.

Continuity mistake: The view out the back of the barn door when it's first revealed does not match the same view, just minutes later, in the final shot of the film. (01:55:43 - 01:59:12)
Continuity mistake: When Bing Crosby and Danny Kaye enter the club car on the train when heading to Vermont, Bing Crosby puts his suitcase on the floor next to the booth in which they are seating. In fact, Bing places his hat on the bag. The ladies enter the car, join them for a talk (and a song) but when the group gets up to leave the bag is missing.
Continuity mistake: During the Choreography number, Danny Kaye's hands/positions keeps changing during the beginning part.