When Monique comes to visit her best friend, she, who is supposed to be French and does speak with a French accent, says "S'il vous plaît" when asked if she wants a drink. But there are 2 errors in this one statement. As a best friend, she would say "tu" not "vous" which is the more formal term. And she also mispronounces plaît. The T is silent, but she puts an S on the end of the word which isn't even there. It immediately told the audience that the actress didn't speak French.
When Ava goes for her CT scan, they show her going into the machine. She is wearing her wedding ring. No metal at all is allowed during a CT scan in real life.