Other mistake: There are heavy winds and persistent snow in an alpine resort, snowing every night, but throughout the whole movie even when Lombard goes to check the open door at night there's no hint of breath cloud on anybody.
Other mistake: The singer dies like he's been shot, screaming out and with a violent movement. Nobody in their right mind would say that he passed out drunk, but a couple of guests just assume that. Somehow with such a theatrical and violent death the glass stays also intact and with enough liquid to be examined later. (00:23:40)
Other mistake: When the General tells the story of how he received the invitation, he mentions that Owen claimed friendship with someone else who was also supposed to be there. Turns out that the Judge was supposed to meet 'legal friends', and Mrs. Bergen meet people from the film business. It's hard to imagine how anyone - especially one with the General's temper, or a capricious film star - would fail to mention the fact earlier and calmly go on with the situation when it should have been obvious hours earlier that the people they were supposed to meet not only were not there, but were not expected nor even supposed to be. Anyone would have been livid about being so blatantly conned from the beginning. (00:19:00)
Other mistake: Lombard supposedly just pretended to drop the key inside the chandelier while he palmed it instead, but A) you can see the shadow of the key in the glass bowl and B) the noise comes with a timing and pitch that could be explained only by a key dropped, not banged against the rim. (01:11:05)