Continuity mistake: After Mr. Gustave and the other inmates eat the Mendl's pastry, while discussing an escape plan, one of the inmates has the Mendl's box held close to him. The condition of the box, the position of the lid of the box, and the position of the ribbon on the box changes numerous times between shots. (00:43:03 - 00:45:10)
Continuity mistake: Agatha's nightgown strap switches between hanging down on her arm, or being up on her shoulder, normally.
Continuity mistake: When Zero and Mr. Gustav are discussing things in the courtyard right after Mr. Gustav escapes from through the sewer system, Zero's bag strap switches between across his chest and hanging by his side in different shots.