Goofs

When Omar spreads out the girly magazines, the distribution of the magazines on the floor is noticeably different from the close-up to the long shot.

When Darryl throws the bowling ball through the window, it leaves a large round hole but the rest of the window pane remains. About two seconds later, the boys scramble out the window which is suddenly completely free of glass--not even jagged edges around the frame.

When Arcane re-captures Abby and returns her to his mansion, it seems like dozens of guards in front of the house are frantically running past them in both directions, presumably to defend the mansion from Swamp Thing. In one long shot, you can see an extra dressed as a guard running right-to-left, then stopping, turning, and running left-to-right. This reveals that the multitude of hustling guards were actually a far smaller number doing circuits in and out of the camera frame.

When Abby arrives at the mansion, Arcane tells her to settle in and they will talk at dinner. However, they are not shown having that dinner until the evening of the following day. No explanation for the 24-hour delay is given in the film and Abby is not shown doing anything during the extra day.

When Lana prepares to take a bath, she starts filling the tub then walks away wearing only a bathrobe. A moment later, she's in the hall at the elevator door, where she gives the jeep keys to an escaping Abby. Presumably, Lana then enters the elevator because Swamp Thing does not encounter her as he exits her suite (after entering through the bathtub pipes). So, the plot hole is there's no apparent reason for Lana to start filling the bathtub then immediately leave her suite in her robe with the jeep keys intending to go to another part of the mansion via the elevator.