Plot hole: When Wade and Art3mis are in the dance club he uses Zimecki's cube to turn back time 60 seconds. But the time from when IOI crashes through the roof until Wade uses the cube is 75 seconds. So IOI still would have been there for 15 seconds. Not to mention the fact that it just automatically seems to know that it wants the user and Artemis to also be immune to this silly time reverse effect.
Other mistake: When Helen turns right to "head to the stacks" everyone in the back of the van falls to the right. Centrifugal force would push them to the left. (01:56:06)
Continuity mistake: At the start of the movie, they mention that Planet Doom is in Sector 12, but they later mention Planet Doom is in Sector 14.
Visible crew/equipment: A cameraman can be seen in the side mirror when the van stops to pick up Artemis.
Continuity mistake: Towards the end of the movie, Halliday shows him the self-destruct button. When the van gets hit, he slams into the wall, almost pressing it. Before the van is hit there are controllers hanging on some wooden hanger right under the button, but when he trips and his hand is on top of the button, the wooden hanger, and the controllers magically disappear. (01:59:35)
Continuity mistake: After using the Cataclyst to wipe out everyone, Sorrento exits his gaming rig, falling to his knees and removes the groin section, handing it to the guy as they walk through the door. Next shot we see Sorrento with the piece back in place. In fact, he runs his hands over it as he walks past.
Continuity mistake: During the battle on Planet Doom, Art3mis jumps into the DeLorean to tell Parzival that they're "playing Adventure." She jumps in through the windshield. When the shot changes, the hole in the windshield is now larger.
Other mistake: When Wade is explaining his past at the beginning, he says he was born after the corn syrup droughts, after the bandwidth riots, after people stopped trying to fix problems and just tried to outlive them. Then he says his parents didn't make it through those times. So, how was he born?
Revealing mistake: Just after Wade gets threatened and his home is about to be bombed, he leaves his van trying to call his friends. After this shot, the camera pans over a load of scrap cars. Whilst the movie is meant to be set in America, at least 3 UK registered cars are visible in amongst the scrap cars, still wearing their UK plates. These 3 rather unremarkable cars, a Ford Mondeo, Fiat Punto, and Ford Fiesta Courier van, are unlikely to have ended up in the US.
Suggested correction: Though unlikely, not impossible. This is a future scenario and it's not far fetched to think that some economic crisis prompted people to buy import cars and then never given US plates. Or they were imported for parts. Or some UK workers using their own car.