Continuity mistake: During the scene where Lewis is first on the roof-top, and Mildred comes up to speak with him, the box he is sitting next to is plain wood on one side, and tallied on the other. When there is a close-up of Lewis' legs and the torn paper, when he's ripping the pages out of his book, the box has stencilled writing that is upside down. (00:06:25 - 00:18:30)
Factual error: Goes along with the other factual error about the time machine: when Lewis falls, he falls into the bottom of the time machine, but when it becomes visible, a bit of roof is over his head. How could he go through the back half of the roof, but not all the way through the time machine? (00:20:35)
Other mistake: Right at the beginning of the movie, when Lewis's real mum picks him up from the box and hugs him, it's no more than three seconds before she hears Lewis from the future slipping on the step. She gets scared and puts baby Lewis back in the box. When Wilbur takes Lewis to meet his mum, near the end of the movie, the time his mum holds the baby is more than twenty five seconds.
Continuity mistake: When Lewis is tearing out the pages of his notebook, his bag is open. When he discovers that Wilbur is not a cop from the future - from the tanning salon coupon - he goes to grab his bag. This time his bag is closed and in the opposite position.
Factual error: When Wilbur tosses Lewis onto the time machine, he should have broken or hit the glass covering the back half. And he is on all fours when the machine becomes visible, which shows he would have had his face hitting the driver seat, yet he scrambles back into the passenger seat without a problem, then is seen barely leaning forward to talk to Wilbur in the future.
Continuity mistake: When the time machine crashes, Wilbur is holding the detached steering wheel. In the next shot, the wheel is still attached.
Revealing mistake: Near the end, right when "little wonders" starts, Lewis takes a moment to look at his future family, Lucille, Frannie, etc. When there's a closeup on Lewis, his memory scanner reveals a reflection of no one in the gym, except for Lewis, even though people are supposed to be standing in front of him.
Continuity mistake: In the scene after Lewis and Wilbur crash the time machine and are pushing it across a huge field, right before Lewis says "What about your parents?" the shadow of the time machine looks as if it's noon. In the next shot, when Wilbur responds "Mum never goes." the shadow is completely different. It's now to the left of the screen.
Other mistake: In the beginning, when Goob falls asleep, he misses the catch, by almost a foot or so. At the end of the movie when Lewis calls out to Goob, the ball lands on his head, and drops into his hand. Since Lewis didn't alter the timeline to where Goob is standing, (as to the part of not inventing the helping hat) Goop should have been in the same spot.
Continuity mistake: In the very beginning, when Lewis' mother is delivering Baby Lewis to the orphanage, the light reflected on the building to the left of the orphanage changes dramatically throughout the scene.
Plot hole: When Wilbur and Lewis are time traveling for the first time, Lewis says he's done with the memory scanner. Since he said he wouldn't invent Dor-15, and she went away, wouldn't the time machine and everything else in the future go away since the memory scanner started it all and Lewis decided to quit?
Suggested correction: Lewis wasn't fully giving up. He was just frustrated and probably went back to it later anyway. Whereas with Doris, he deliberately decided not to invent her because of the danger she posed.
Other mistake: In the beginning of the film when Lewis is dropped off at the orphanage there is a blue car parked in the background. This is the same exact car (license plate and all) that he is driven away in when adopted at the end.
Suggested correction: There are 3 options: First, it may be a car that hasn't been sold to their future owners (Bud and Lucille) since it was still in the past anyway. Second, if it is proven to be Bud and Lucille's during this time, it could still make sense, as we could see in the ending when Lewis tests his memory scanner that Mildred (or the orphanage lady) was present in their wedding. Third, it's also possible that it's just the default model for the car and we weren't supposed to see it.
