Keep Circulating the Tapes: Both Canada and Australia only got two DVDs. The Canadian DVDs contain 4 episodes each while the Australian DVDs contain 6 each. The entire series is available for free on Youtube in North America, though.
The Christmas and Valentine's episodes "Let Them Eat Fruitcake" and "Pucker Up" were unaired in Canada (due to YTV wanting to save them for the proper holiday, only to can the show soon after). However, they did air in Australia.
For unknown reasons, the UK got "Pucker Up" (airing it even when it wasn't Valentine's Day) but not "Let Them Eat Fruitcake".
Playing Against Type: Lyon Smith usually appears as the voice of cocky protagonist-type characters like Corey Riffin on Grojband, so hearing him as the slimy Roger Pinkeye is a bit surprising for some.
Talking to Himself: In "Oldie But a Goodie" aging Abby and her mom have the same voice actress. Abby actually lampshades this, complaining that she's starting to sound like her mother.
Concept art posted online by Lab Rat's voice actor Deven Mackon his Tumblr reveals that the show originally opted for a completely different, more traditional Thick-Line Animation style. In this version, Abby had short pigtails instead of the long ponytail seen in the show and Ty had a more cleancut appearance rather than the Anime Hair he possesses in the show.
The Grossology team was originally much more diverse. Aside from Abby, Ty, and Lab Rat, there was also a British boy based on Harry Palmer named Nigel Stodding, a beatnik with pinkeye named Pink Eye, a tall Goth girl obsessed with bugs named Creepy Crawly, a short filthy boy named Sloppy Joe, and a boy named Colin Polyp. While Nigel and Colin were completely scrapped in the final product, Pink Eye, Creepy Crawly, and Sloppy Joe were redesigned into some of the show's villains (with the first two becoming Roger Pinkeye and Insectiva, and Sloppy Joe keeping his name). See here.
Lab Rat was originally designed as an overweight Caucasian boy and was to be voiced by a child actor. Deven Mack, before he auditioned, actually got a hold of the design and initially did an audition doing an impression of Otacon from Metal Gear Solid. However, the producers wanted Mack to re-do the audition in his natural voice albeit with some Chris Tucker influence. After complying, not only did he land the role, but Lab Rat was redesigned to more closely resemble his new voice actor.