Revealing mistake: When Vida, Noxema and Chi Chi decide on the convertible they pull forward a few feet. The catch their "reflection" in a mirror of some sort. When viewed with great scrutiny we see that in fact this is not a mirror reflecting their image but a camera shot of them that has been reversed. The special effects guy placed the lights around the clip to make it look like a mirror. When seen numerous times we can see the image shake a bit and that the image moves ever so slightly within the light bulb frame. (00:17:50)
Revealing mistake: When Kit Li takes off in the hijacked police helicopter, and the first time the copter's fuselage is fully visible, it is obvious that the rotor blades are turning too slowly to ever facilitate lift-off. (01:20:40)
Revealing mistake: The mix of two shots is obvious such as the photographer inside the centerfold's top.
Revealing mistake: When the family heads to Sears and are first playing with the cameras, Jan's show that her movements in her camera are slightly different and not the lag factor of the image being displayed on the TV.
Revealing mistake: When the Parker Brothers run to the side door of the ghost-train, which is supposedly in Blackpool Pleasure Beach, you can see it's a fake set built in a carpark, because the carpark bay marking lines disappear under the wall of the ghost-train. (00:29:35)
Revealing mistake: When Brodie and TS are first approaching Jay and Silent Bob there is a very noticeable jump cut just before Brodie says "Hey Jay." [May only apply to the Blu Ray extended edition of the film.]. (00:33:15)