Visible crew/equipment: Just before Clark goes down the hill on the saucer sled you see the view down the hill. If you look carefully at the right of the screen you can see two pinkish cables stretch into the distance. These are the pyrotechnics that make the explosions Clark sets off. You can see it clearly on the DVD version, but not too clearly in the VHS one. (00:50:15)
Visible crew/equipment: When Clark gets his "Christmas bonus" he starts going off about what a lousy guy his boss is. During his outburst you can see a crew member's head pass by the bottom left corner of the screen. (01:15:55)
Visible crew/equipment: When Clark is on his sled, just before he crashes into the cabin, the shadow of the camera is visible on it. (00:50:50)
Visible crew/equipment: After the cat is electrocuted and begins smoking underneath the chair, the next camera angle still has the smoke machine in the shot next to the chair.
Visible crew/equipment: When Eddie and Clark are putting the burned chair in the garbage, you can see the shadow of the camera following them.
Visible crew/equipment: Just as Clark begins his explosive argument, there is a shot of the family watching in horror, and the top of the set is visible at the top of the frame.
Visible crew/equipment: When Ellen opens the door after Clark falls from the tree, there's a strange white thing visible for a few frames at the upper left of the door. Might be the hand of a crew member opening the door.
Visible crew/equipment: Just as Clark is about to smash through the hut on the greased up sled, the shadow of the camera is on the hut. (00:50:57)
Chosen answer: Because there was cat food in her jello mould. He's pointing out the absurdity of someone adding cat food to jello.