When Tom McHugh puts the birthday button on the drapes, the lights in the room are off. In the next shot, when Lew's henchman falls from the building, the lights in the room are on.
When Dwight is banging on the trunk towards the end of the movie, no bullet hole is visible.
When James Lew's thug attacks Tom McHugh in the dark, he does a flying kick and goes crashing through the window several stories up. But when the camera cuts to outside the house, as he falls, the room's lights are suddenly back on.
When the police officer is recording the statement of the suspect, there is no tape in the machine.