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".
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