The second time Renoir draws Andrée, after sending Coco/Claude away, the shot of Andree topless goes back and forth, each time her hair changes from draped over her front to behind her back. It is so obvious it's hard to believe anyone missed it.
When Pierre-Auguste walks in on Jean Renoir being bathed, a modern toggle-style light switch is visible on the wall. The toggle switch wasn't invented until 1917, which is a few years after that part of the film. Earlier light switches were push-button style, and the switch on the wall is also of a modern plastic style that is very much later.