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 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: The mix of two shots is obvious such as the photographer inside the centerfold's top.
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)
Revealing mistake: When Katie is making Sharkey levitate as part of her circus act, you can see the shadow of some rigging connecting him to a nearby pillar. (01:43:50)