Continuity mistake: When Sam is making grilled cheese sandwiches with the ironing board and iron, he finishes one sandwich and places it on top of another on the side table. After Joon's explanation of cheese and culture the camera cuts back to Sam placing another finished sandwich on the side table on the same place that he placed the first but there is only one sandwich there where there should be two.
Continuity mistake: When we see Joon's medical records at Dr Garvey's clinic her address is listed as 'N 825 Water Street', but when Joon produces her Medical Alert card as a form of ID to the cop in the next scene it shows her address as 'N 301 Cedar Street'
Continuity mistake: In the scene where Sam is doing his Buster Keaton act, his tie is done up. When he jumps in his hat it's down, then when Benny is helping him up it's back up again.
Continuity mistake: When Benny and Joon are riding in the car to Benny's friend's house, Joon looks up at Sam in the tree. This scene is in slow motion, and we can see Benny's hand turning the wheel sharply to the right to turn into the driveway. There is another shot of Sam in the tree, then the shot of Joon is recycled -- Benny's hand is again moving the steering wheel sharply to the right.
Deliberate mistake: In the scene where Sam is swinging from the hospital window, you see him first from the inside. Now he is obviously being pushed (from a crew member) so it looks like he's moving back and forth smoothly. However, when seen from the outside he couldn't be pushed and so when swinging by himself, he was actually bouncing off the walls. Inside this would have been seen. Also, inside it seems that the sky is clear, though outside there is a tree by the window.
Revealing mistake: During the opening credits, it is obvious that the train is just a model during the initial close up shots.
Suggested correction: There is nothing in the opening shots that betray it as a model shot. Logic alone argues against it. Why would they go to the expense of building a detailed model when there is no unusual action or angles required? Especially since many of the shots are obviously not a model. Exactly how is it obviously a model?
I agree it does look like it's a model train, but that's only because of the filming techniques that make it appear to run a little choppier like it's was a light weight model. But it's real, for example in one scene that looks like it's a model, you see a real bird flying on screen.
Visible crew/equipment: When Benny comes home from work and Mrs Smail is about to leave there is a crew member leaving through and closing the backdoor. He has short blond hair, and looks to be thin and a bit on the tall side.
Suggested correction: That is not a crew member. It is Joon, leaving and slamming the door after her argument with the housekeeper. The fact that we can hear the door slam shows it was not an error.