In Season 7 episode "The Cookie Clause", Alton Brown mentions using cocoa powder to hide mistakes with coloring frosting. Santa turns to the camera, stroking his chin and murmuring "cocoa powder". The same actor who played Santa also plays Cocoa Carl, one of Alton's Sitcom Arch Nemeses.
The same actor also showed up as an appliance salesman in the souffle episode, leading to a You Look Familiar moment at the end of the scene.
Doing It for the Art: Alton never made any money off of Good Eats itself, instead pouring what would have been his salary back into the show's budget. He makes all his money off of merchandise, writing, and advertising (like the series of ads for Welch's grape juice).
One of the producers even agreed to construct a new home around a kitchen specifically designed to allow for production of the show within said home/kitchen (this would be the "set" used for Seasons 5-8). Complaints from neighbors eventually forced the show into a lookalike studio set for the remainder of the production run.
And while we're at it, it might be no coincidence that Alton voiced himself in a Good Eats/Archer crossover (yes, this happened, as a DVD bonus)
Real-Life Relative: Alton's mother appears in "Romancing The Bird"; his (now deceased) grandmother was in two episodes (fruitcake and biscuits); his daughter appears in several episodes; however, his wife (who is also a producer) did not appear outside of the curtain call on the 10th Anniversary special.
What Could Have Been: On an episode of the Nerdist AB mentioned that he was able to figure out a way to effectively cook a whole pig with just 75 dollars worth of gear from the hardware store. Unfortunately, the executives at Food Network vetoed it because they said no one would actually try it.
Every time Alton says "but that's another show"...and we never got that episode.
W, aka Vicki Wong, is played by Alton's chiropractor, Vickie Eng.
In the book Good Eats: The Early Years, Alton says that everyone who works on the show does so with the understanding that, one day, they'll be appearing on-camera in some capacity. Thus many characters in the series are members of the staff (exceptions are actual food experts such as Deb Duchon the nutritional anthropologist, Shirley Corriher, and a few recurring characters that are hired actors such as Marsha, Elton, Cocoa Carl, Chuck, etc).