Revealing mistake: When Allie goes to vomit, the toilet moves like a prop. (01:18:00)
Suggested correction: Have you ever lived in a New York apartment? I've had toilets that weren't fastened to the bathroom floor at all and was still charged 900 dollars a month in rent. It's not outlandish to think the bowl might wobble a little if the superintendent has been lazy. That elevator in the basement is still broken, after all.
Revealing mistake: After Allie writes the suicide note that Heddy dictates to her, Heddy fires her gun but it has the safety on it.
Revealing mistake: When Hedy, pretending to be Allie, tricks Sam by giving him oral sex, the camera shows where her head is when she is supposedly doing this - and her head is in line with approximately his ribcage. Unless Sam had some sort of medical anomaly, she was quite a bit off the mark, so to speak.