When Garrett originally announces the Halloween party at Bram's, he tells people that it's on Friday night. However, when Simon later invites Martin to the same party, he tells him it's on Saturday.
When Simon eats with his family, Simon's phone says that it's 3:20, yet when he goes outside to read Blue's email a moment later in the patio, it's pitch black dark.
"Blue"'s e-mail address changes throughout the film. In some scenes, it's "Blugreen118" and in others, "Bluegreen118".
At the Halloween party, after Leah puts the "Ronaldo" label back on Nick's shirt, the position the label is in on the shirt changes in each shot. Leah puts it a little bit above the number 7 on Nick's shirt, but in the next shot it covers the top of the number. It then moves back up later on.
At 28:35 in the movie, when Simon steps away from supper and goes outside to read an email from Blue, the subtitle reads "BRAM: Jacques, I have to get something off my chest", instead of identifying the writer as BLUE. At that point in the movie, neither Simon nor the audience knows for sure that Blue is Bram.