Deliberate mistake: When Prince Henry was sitting on the porch, there was snow accumulated all along the inner side of the railing - but the attached perpendicular boards (about 4" high) on the outside should have blocked snow, or that amount of snow, from accumulating there. (00:42:30)
The Winter Palace (2022)
1 deliberate mistake - chronological order
Revealing mistake: The chalet was visible behind Emily when she was outside talking on the phone, but subsequent views of Emily showed her in front of a solid white background (mimicking snow) - indicating the use of a green (white?) screen. (00:13:34 - 00:13:56)