Continuity mistake: The cut (s) on Jim's lower left lip frequently changed. At the "Wildcats" game, there appeared to be three slits, but they were not easily seen and it wasn't apparent how he got them. In the earlier beating he got from Lee's Heavy #1 and 2, his lip didn't get cut and the previous cut on his lip was not visible. When Jim met with Neville, he had three distinct vertical slits/cuts on his lower left lip. Thereafter, the appearance (presence or absence) of these cuts continued to vary. (01:25:55 - 01:31:45)
Revealing mistake: The (CGI) wind turbines were awkwardly spaced and incomplete in spots. Ten or more sets of blades (center left of screen) had no towers attached to them - just blades "in the air." The blade lengths varied from tower to tower instead of being uniform and appeared to be disproportionately small relative to the tower heights. Nocelles were absent (or not visible like they should be), so there were no anemometers attached. Most towers did not appear to have a transformer at/near their base. (00:59:07)
Deliberate mistake: Jim was sitting on a bench along the road and Amy [Brie Larson] walked by (several feet away), apparently not noticing him. (Jim was seated between other people.) Brie got into her car and adjusted the rearview mirror, catching sight of Jim on the bench. A driver would adjust the rearview mirror, if necessary in the first place, to align it with the rear window, not angle it to the right to be able to see the sidewalk. (00:51:34 - 00:51:55)
Revealing mistake: When Amy was walking past the bicycle rack along the road, the background changed a few times (indicative of using a green screen) and she walked past the same bicycle rack at least two times. Sometimes, there was no bicycle rack visible, although Amy had not walked very far. (00:51:00)
Continuity mistake: Amy set Jim's book perpendicular and very close to the desk's front edge and the pen was diagonal on the book's cover but not close to the desk's edge. When the book came back into view, the pen had been straightened and moved closer to the desk's front edge. (00:36:30)
Continuity mistake: A side view of the tennis court observation tower shows the umbrella angled around 45°, arched over Jim's head. A front view shows the umbrella behind Jim's back, more perpendicular to the ground. In the next rear view, his body is tilted toward the right, the umbrella is arched half-way over his head again, and his legs are no longer crossed. The next front view shows the umbrella in back of him again (more parallel to his upper body) and is fanned out backwards to not obstruct his face. (00:26:42)
Revealing mistake: The room Jim and Neville are in is equipped with a double interior wrought iron security gate that appears to be automated, but it does not actually function like a motion-sensored one typically would. The double doors are open before Neville's bookkeeper exits, and where Neville is standing might explain why both sides of the gate are open and stay open until the bookkeeper re-enters. However, they close behind the bookkeeper (and at different rates), even though Neville has not moved. (00:09:26)
Continuity mistake: Mr. Jones used his left hand to smack Jim across his right cheek/face. The injury Jim suffered (when it was even there) was on the left side of his face. The vertical slit (cut) on the left side of Jim's lower lip when he was in his office was not there (or too faint to be seen) when he was talking to Amy in the hallway. When Jim exited the building, the cut on his lip was obvious but the bruise on the left side of his face was more above his eyebrow than on the side of his left eye. (01:11:11 - 01:14:54)
Continuity mistake: In the empty (drained) swimming pool, there was a chair on its side with its back facing Jim. After Mr. Jones smacked Jim (but was not close enough to move the chair), the chair was on its back and at a different distance to the mat. (01:09:11 - 01:11:22)
Continuity mistake: The broom (?) handle that was sticking out of the pile of plastic was leaning into the corner of the empty swimming pool. At a more distant view (opposite end of the pool), it should have been visible but was not. In later views, the handle's position varied - straight up (not diagonal) and leaning in a different direction. (01:09:19 - 01:11:44)
Revealing mistake: Neville pushed Jim's back against a metal garage door/gate in the alley. Front views of Jim show him with his back (and head) against the door, but rear views show him out in the open (away from the door/walls/buildings). (01:01:42)
Plot hole: Lamar was a star basketball player who didn't pay attention in Jim's English Literature class (and wasn't "good in English") but needed to pass to continue playing. Lamar told Jim, "I've had four courses with you" and "I'm a Junior." Whether this was Lamar's 4th or 5th English course, neither make sense. A fourth course would equal 12 credits - enough to be Lamar's' declared major (unlikely) - and most students don't enroll in the same professor's courses when they don't do well ("easy A"). (00:43:56 - 00:46:40)
Revealing mistake: Jim parts his hair on the left side. The stacks of his books on display in the hallway include a photo of him with his hair parted on the right side, but otherwise looking the same. Hair that is persistently parted on one side will not easily part on the other side and lay across the head in the same way. (The image was reversed). (00:25:20)