The show didn't actually own a Volkswagen Beetle when they were ready to plan the vehicle's conversion to a Swamp Buggy. So, they rented one and used it to plan the conversion, then managed to buy a Beetle by the time the conversion was performed.
Host/star 'Jesse James' became an ordained minister through the Universal Life Church during the Chevy Suburban/wedding chapel conversion, specifically so that he could be the one to perform the marriage ceremony which signaled the completion of that episode's challenge.
For the episode where a Mini Cooper was converted into a snowmobile, a brand new 2003 Mini was supplied free of charge by BMW, and Polaris Industries supplied all the parts necessary at no cost.
Strictly, a "factoid" is a piece of believable, but untrue information, not a "small fact" (although, given that the Monster Garage Factoid above is untrue, it would seem that on this occasion, at least, it was used correctly).
A Monster Garage Factoid during the "Ambulance/Wheelie Car" episode refers to Hemi Under Glass as a Dodge factory reject. Hemi Under Glass was actually a Plymouth drag racer.
In the "American Monsters" episode, the narrator introduces the suburban mechanics by saying their Deloreans were high style in the 1970s. The Delorean didn't start production until 1981.