In the scene where the orphans are looking at Aunt Josephene's pictures, they come across a picture of the "Spyglass Group" that their parents, along with Uncle Monty and Aunt Josephene belonged to.
If you pay attention, in the movie, Violet discovers this picture after turning three pages in the album, but you can see it before she mentions it.
The second page turn takes place after Aunt Josephene explains how she was adevnturous while her husband was still alive. Right after she says this line, while she is still in frame, Violet turns the page. If you pause the video right after she does so, and look at the next page, you will see the photo laying sideways and out of focus in the frame.
The reason this is a slip up, is because the next shot shows Violet turning the page a third time before noticing the picture. It mysteriously jumps from the 2nd page to the third.