Continuity mistake: When Ms. Heller is talking to the tour guide at the museum, she offers her a $5 bill to take the tour twice. How the bill is folded and held changes. When Ms. Heller says do the tour twice it's pinched between her fingers, then it's folded in half. It keeps switching between folds. (00:35:19)
Suggested correction: I didn't see it folded at all. The "other half" or part of the $5 bill that you can't see is actually squished/crumbled in the palm of Heller's hand.
The mistake is partially valid, its position changes. You seem to be talking about when she has the $5 and camera in her hand. When she says do the tour twice, it's pinched between her fingers, then in the next shot, it's folded in half, then she's pinching the end and the other end is unfolded, then back to folded in half.
Regarding the "folded in half" - the $5 bill is folded, but VERTICALLY. The differences that are shown appear to be deliberate SLEIGHT OF HAND. Heller is flashing the whole $5 bill at first, then crumbles it (symbolizing it "going away"). By having the $5 folded vertically, Heller was able to quickly fan out the left side (part equivalent to a flat $5 bill), then hold the $5 to resemble a bow tie. Folded vertically, the $5 bill could be manipulated to look different and more or less appealing.
She never crumbles the $5 bill during the part the mistake occurs. The way she's holding the bill changes between shots, meaning no time elapses, so there can be no deliberate sleight of hand.
Or would that be HORIZONTALLY? The $5 bill is folded to be long, not short, if this clarifies what I'm trying to say.
Other mistake: If Harry was born in 1969 and is 18 when he attends school (based on "8 years later" then "10 years later"), then the year should be 1987, not 1986 as the movie states. (00:01:25 - 00:01:52)
Suggested correction: This isn't necessarily true. The +8 and +10 years don't have to literally be to the day. Maybe Lloyd hasn't had his 18th birthday yet - it could be days away, making 1987 valid. Lloyd was born in 1969, but I don't think that was indicated for Harry. Harry was "held back 3 years", so may have been born in 1968 in order to be in the same grade as Lloyd, who was held back two years. Otherwise, Lloyd would be a sophomore and Harry a freshman, which questions how they're in classes with jrs/srs?
First off, the mistake isn't focused on anyone's age, just the date. Second, we know Harry was born in 1969 since the film starts with his, so your comments don't make sense. It says 1969 and the 8 years later followed by 10 more years later, which would put it at 1987.