Other mistake: When Reuben and Leland are playing racquetball, Leland loses a tooth. When he opens his mouth to take it out, you can see the space where it's missing. However, when it cuts to Reuben, you can hear the sound of Leland yanking it out of his gum.
Other mistake: When Reuben and his boss are in the restroom and are going, if you look in the toilet there is nothing going in. (00:13:35)