Visible crew/equipment: When Doug is pitching his idea to Christian, they are outside on the terrace of the hotel. As Christian is walking inside, he walks past some windows and you can see the camera and the crew in the reflection.
Visible crew/equipment: When Rosie O'Donnell's dog is chasing the neighbor's cat, it it very clear there is a stuffed cat attached to the camera to lure the dog to follow.
Visible crew/equipment: When the alien ship is lifting up the Coneheads in their red car and the two Federal agents with its magnetic gripper, as they get closer to the ship's lights, you can see safety wires, either for the car or the two men.
Suggested correction: What you're seeing is the car's antenna.
Visible crew/equipment: When evil Debbie Jellinsky is electrocuted, two stunt wires/cables are visible on her shoulders in the first close-up shot.
Visible crew/equipment: When Mario is telling Luigi about getting a call from the café for the plumbing job at the start of the film, watch the cabinet with the glass doors behind Luigi. At one point, you can see the reflection of a crew member in a short-sleeve shirt for a few seconds.
Visible crew/equipment: When Henry and Charles are released from prison after the subway fight they are walking across the street discussing their next plan and then stop on the side walk. In the background you can see a woman with a radio redirecting pedestrian traffic on the sidewalk away from the movie set. A few men stand around asking her questions and watching the actors. (00:47:53 - 00:48:43)
Visible crew/equipment: When Benny comes home from work and Mrs Smail is about to leave there is a crew member leaving through and closing the backdoor. He has short blond hair, and looks to be thin and a bit on the tall side.
Suggested correction: That is not a crew member. It is Joon, leaving and slamming the door after her argument with the housekeeper. The fact that we can hear the door slam shows it was not an error.