When the bed is being towed through winding roads with the Harts inside, they are seen sitting up in the close-ups but the first few long-shots show bed-sheets covering bodies.
Then mannequins are seen sitting on the bed, standing-in for Robert Wagner and Stephanie Powers.
The bed crashes through a fruits & vegetables stand, sending produce flying and landing on the bed. In the close-ups there is no fruits on the bed.
As Jennifer, Stefanie Powers keeps her fingernails rather short. The fingernails of the hand seen touching the headboard are much longer.
2) She then barely wipes the headboard again and the entire painting is seen completely revealed in the next frame, without any traces of the top paint. This would be impossible to do in reality so fast and---again---without the proper chemicals.
At 22:56 the Harts make off with the bed and the sheet covering it is supposed to look like it blows off. Instead, the sheet is pulled off via a wire and pulley. The person holding the wire let go so the sheet falls to the ground. The handle they were using is pulled forward by the pulley and you see it strike the ground and get dragged for a moment on the right side of the road behind the actor chasing the truck.