When Uncle Phil talks to Lisa about proposing, he puts his hands in his pockets. In the next shot his hands are still at his sides, but in the next they are suddenly in front of him, at about chest level.
After Will collides with Geoffrey in his wheelchair, it cuts to a shot of Hillary then back to Will, and his wheelchair is positioned differently. Also, Geoffrey has vanished and Vy is suddenly standing next to Will.
Jazz plays with an defibrillator and electrocutes himself. Although these devices have a built-in battery, they're supposed to be kept plugged in. Not only is this one not plugged in, it doesn't even have a power cord.
Will is hospitalized but isn't wearing an ID wrist strap.
Will asks the nurse if he'll be able to slam dunk once he's healed. After she tells him he will he says "That's good because I never could before." There have been a few times throughout the series where Will has been shown slam dunking a basketball.