During the end sequence where Liza is pursuing Jude through the old house a sign can be seen on the wall stating that rule #10 was "Kiss Goodnight" However earlier in the movie when the rules are listed and given to Liza "Kiss "Goodnight" is actually rule #9.
The newspaper article about the 1958 murders identifies the issue date as a Wednesday when that date was a Thursday.
When Liza is reading a book , while Brahms is in Lounge and the TV comes on, the page is blank when the book opens then she turns page and there is print on page.
At 1:02:23 the girl has her eyes shielded by her mum.
That's way past the girl seeing the traumatic event of her brother being hurt.
Although the guest house was supposed to be set in England, the power sockets and light switches are of US origin.
There is no way to glue a porcelain doll's head back together after it's been smashed into thousands of tiny pieces.