Corrected entry: In the scene in the school gym, circa 1989, when the big game is just about to start, Ned (the little buddy) runs in late, wearing a robe and pointed hat. He says he was late because of some Harry Potter / Gryffindor activity he was doing. The problem is: the first Harry Potter book was published in 1997, and this part of the movie takes place in 1989. There is no way a character in 1989 could know about Harry Potter.
Corrected entry: When Alex is tied up in the bathroom, "Mark" says "You're Uncle Ned's kid" but Alex is Mike's kid.
Correction: Wrong "your." "Mark" says, "I'm Mark Gold, your Uncle Gold's kid." He's referring to himself being the son of Ned.
Corrected entry: If Mike's girlfriend got pregnant in high school in 1989, and the movie takes place 20 years later, how can his daughter still be in high school?
Correction: The younger Mike could be about to turn 18 and so assuming Scarlet was a month gone 8 months later would mean Mike would have been 18 when the baby was born. The older Mike could have only just turned 37 so it is possible that his daughter is 18 years old as seen in the film (she's a high school senior and so would be around 18).
Corrected entry: The high school basketball team is the Warriors. During the credits, they are flipping through the high school yearbook. They come across a basketball player's picture, but on the jersey it says "Panthers."
Correction: During the credits they are showing pictures of those people who helped create the movie when they were in high school, not people from the fictional school.
Corrected entry: At end of the film, during the last game, Zac is wearing a No. 3 jersey. He goes into the hallway and it turns into a No. 4 jersey. He swings around his wife and the jersey is back to 3.
Correction: It remains a number 3 jersey throughout the entire scene.
Correction: He doesn't speak about Harry Potter, he says something about what kind of wizard would he be if a quest during a battle with a hippogriff, the hippogriff is a mythical beast, he was probably playing Dungeons and Dragons.
Specks
Ned mentions being an good Dungeon Master because he didn't leave in the middle of the fight with a hippogriff. Although a hippogriff is mythological, it was created in the Harry Potter Universe which, again, didn't exist at the time.
Hippogriffs were not created by J.K. Rowling! They are ancient Roman mythical creatures first mentioned in writing by the poet Virgil (who died in 19 B.C.) They are also creatures used in D&D games.
Bishop73