Continuity: When Calvero has returned to the flat after his failure to revive his career at the Middlesex Music Hall, Thereza is sitting in an armchair, which has a blanket draped over the back. For most of the scene, when you see her in close-up, the blanket is folded over the middle of the chair-back, and so part of the chair-back is visible. In the long shots, however, the blanket is unfolded and draped fully, covering the chair-back. Towards the end of the scene of Calvero and Thereza's conversation, this is fixed so that the blanket is always folded and draped over the middle.
Continuity: When Calvero returns after his failure to revive his career at the Middlesex Music Hall, the clock on the mantelpiece behind Thereza jumps back and fourth 45 minutes
Continuity: During the final comedy act, the pianist's chair changes between shots.
Miscellaneous: During the final comedy act, the pianist uses "polygrip" pliers to cut the piano-strings, which is impossible. To cut strings you need cutting pliers.
Revealing mistakes: In discussing the ballet with the cast, the director casts a giant shadow over the auditorium (revealing it to be nothing more than a painting).
Factual errors: The film begins in the summer of 1914, as the First World War began, but less than a year passes before a newsboy shows a headline "United States Enters War", which didn't happen until April, 1917. Curiously, only one person appears in uniform, despite England being on a war footing.
Anachronisms: After Terry achieves success, she is shown to tour "the continent", with stops in Paris, Rome, and Russia. The war would have made travel to Russia difficult, if not impossible, and Russia would have been in the midst of the Bolshevik revolution at the time.