Goofs

The same photo of the same man in the same pose is on the front of the book Mallory reads at Michael's house near the beginning, and on the album cover - titled "Peter Sings" - propped up on the table about halfway through.

It was shown where Mallory got the pills to attempt to knock Michael out the first time she tried it, but the second time, after she finished the book and he poured champagne for them to celebrate, not only wasn't it shown where she got pills to put in the champagne to knock him out, but there is no way he would have left anything like that lying around for her to find and use on him again.

Michael doesn't wear glasses to read Mallory's book-in-progress throughout the movie until the last time, near the end. If he didn't need them to read before, then he wouldn't need them the last time; and if he needed them to read that last time, then he would have needed them the previous times.