[Around 49:00] In the bazaar, after Moose died after ate the cake, he re-spawns and lands on a large shelf. In one scene, one can see that the shelf has its right vertical upright totally disassembled from the internal shelves.
A second later, on the left view, the shelf is fully restored in its original state.
At the end of the movie, the kids are wearing new outfits (showing that time has passed from the day they went into the game) they even mention if anything interesting happened over the weekend, yet when they hear the Jumanji drums and then drop the bowling ball, destroying the game, they're wearing the cloths they had on when they went into the game, prior to the weekend.
When Spencer is standing outside the Freak House. Old Man Vreek appears with no red scarf but when the view comes from the car Old Man Break is wearing a red scarf and then it is gone again when the view goes back to a close up.
At 4:08 when Moose enters the scene, his necklace which shows his jersey number 94 is on backwards. The scene cuts to his mother, and then back to him when at 4:23 you can now see the number is facing forward.
While Bethany is composing her selfie, at the beginning of the movie, the coffee mug handle is facing to the left. When the camera angle changes to a wider shot, the mug handle is facing "upward,", which she adjusts to face left. She proceeds to take the selfie with the coffee mug handle facing left.
When Fridge and Stanley are speaking in front of the Freak house, Stanleys raincoat goes from being open at the collar to being zipped all the way up several times as the conversation cuts back and forth between the characters.
When the "gamer" at the start of the movie is playing on the old console he is using a PlayStation controller. While the PlayStation and its controller was out the console shown certainly was not a PlayStation. Also when the console comes back into the movie ten minutes later all the controllers are changed to ones that now match the console.
In the game, Alex does not make a reference to the Will Smith song "Gettin Jiggy Wit It" (which wasn't released until 1997, the year after he disappeared) he merely uses the word "jiggy" which was in popular vernacular for a large part of the 90s.