When Sam and his mom are sitting on the couch, after the operation of Lillian, in the camera shot from the left she rubs her head with her fingers. Then the camera shot turns to the right, in this shot she isn't rubbing her head.
In the very early stage of the movie Sam enters James room. You can see from the window which Sam sits by that it is night time, but they leave the building it is morning time.
When the sodium is thrown into the pool it sinks to the bottom before exploding. In reality sodium floats on water and the explosion is caused by sparks igniting the hydrogen that is formed.
Sam: Six Rules: 1. If you like something because you think other people are gonna like it, it's a sure bet no one will. 2. Most doors in the world are closed, so if you find one you want to get into: you damn well better have an interesting knock. 3. Everything you think is important, isn't. And everything you think is unimportant, is. 4. Don't shit where you eat. 5. Lean into it: the outcome doesn't matter. What matters is that you're there for it. 6. Never sleep with someone who has more problems than you do.
Lillian: I hope you never have to know what it's like to love someone and then find out you're not enough. I was trying to protect you from ever feeling that.