This is one of the episodes the Glooms did not appear.
This is one of the few episodes that takes place entirely at night.
Happy is shown singing the "Most Annoying Song Ever" in this episode with Happy, Sleepy, Dopey, and Sneezy. Later in the beginning of its sister episode, it is shown that he's singing the same song as this episode, implying that this episode took place before "The Enchanted Forest Ranger".
Plot Hole: Doc says he invented his hat. Although in "The Rock of Sages" he states it was passed down from generation to generation, meaning it's unlikely to have been invented by Doc himself.
In this screenshot below, Sleepy is sleeping with a plush that doesn't look exactly like Mr. Hicklepips.
When the 7D arrive at the lab on their scooters singing the most annoying song ever, Sneezy and Sleepy's visors change appearances, plus Dopey doesn't have his on.
Also, as the 7D are circling around the lab Dr. Jingleheimer have already shrunk Jollywood and placed on his play set, but the kingdom isn't on the set. Also in the next shot, Bashful's scooter color changes from blue to orange and he also doesn't have his visor and Sneezy's eyebrows has been disappeared.
Shrunken Dr. Jingleheimer and Bingo aren't in the toy locomotive while Doc enlarges Jollywood back into its original size and back into its place.