Visible crew/equipment: When the Overlord is busy destroying the Diner, when he starts destroying stuff on the counter, you can see the small rods pop up that flip the saucers and glasses into the air. You can also see the compressed air they used, to aid with the effect.
Other mistake: In the scene where Howard falls asleep in Beverly's apartment window and his wallet falls out, she takes out the money. The city on the bill says Washington DC instead of Marshington DC. (00:19:00)
Continuity mistake: At the start of Bev's final sing-a-long before the credits, she steps to the front of the stage with her guitar in hand. In the very next shot, when she starts to sing, a microphone magically appears in front of her. (01:42:49)
Continuity mistake: When Howard and Phil are being chased by cop cars in the ultralight, after Phil says "Trust your birdness - fly!", we see a front-facing shot that shows a cop car pulling up to the right of the ultralight. In the very next shot, no cop cars are even near them, just following. (01:19:55)
Revealing mistake: During the ultralight chase, a police car drives up a hill and overturns. The metal plank underneath to allow for the stunt is visible.
Audio problem: When Howard's couch is about to be sent backwards he says "What is going on here?" but he's not mouthing the lines.
Continuity mistake: When the Overlord is about to explode the Ketchup and mustard bottles, the Ketchup cap is either loose or tight depending on the angle.
Continuity mistake: When Phil explains the ascent of duck, check Beverly's left hand: in some shots it is long enough to touch Howard's elbow, but in other shots her hand has shortened and it's by his shoulder.
Continuity mistake: In the angle shot from the side Phil holds the recorder with both hands, in the angle shot from the front he holds it with his right hand.
Continuity mistake: When Phil meets Howard he takes the recorder out of the pocket and takes it to his mouth. When the shot changes the recorder has vanished and he repeats the previous movements.
Continuity mistake: Howard falls through a ceiling and nosedives to the floor but a shot later he is falling butt first on the couch.
Continuity mistake: When Howard pulls up the microlight throttle the lab building is behind them. A shot later the building is gone and we see the gardens that the microlight passed by several minutes ago.
Continuity mistake: Before the microlight crashes against the banner the people gather on the road. A shot later the road is empty and people are gathering again.
Continuity mistake: Howard asks Beverly where he is and she extends her left arm to grab a bin behind. A shot later her arm is in front of her.
Revealing mistake: When the microlight is about to fall into the lake next to the lab, Howard's POV shows a straight road ahead. However, a shot later the microlight rises from an obvious ramp hidden between bushes which results in a more comedic crash.
Revealing mistake: When Howard climbs up a truck and fires the blast that destroys the laser, he is replaced by an obvious doll, not only does he not move an inch, but when the truck shakes he wobbles as if he was nailed to it.
Visible crew/equipment: When the cop commands Overlord to turn off the engine, a big black tower from the filming equipment is reflected on the front part of the truck. It is not visible in the wide shots of the place.
Continuity mistake: When Overlord electrocutes the cop there's an driver watching everything horrified. His right hand is either lowered or on his face depending on the shot.
Revealing mistake: When the Overlord extends his arm outside the truck, lights up and electrocutes a cop the shadow that his arm casts is not real, but FX made. Problem is, his arm does not cast any shadow on the truck for a couple of shots.
Suggested correction: Again, watching the movie right now. His arm is indeed shown as a reflection.
Continuity mistake: After the duck hunters scene Beverly is inside the truck with her left arm raised. In the immediate next shot it's lowered.
