It is revealed that the Mystery Fellowship, composed by the Darrow Family also had a mascot, a cat named Whiskers. Of all the mystery groups that have a frozen scene in Nightmare in Red, this group is unique because Whiskers is not present, and it was not present in the flashback of Escape From Mystery Manor either, making this episode his first and only appearence.
A laugh track similar to the one used in the original series is heard as the Mystery Machine heads into the sunset.
The visions of the four gate keys associated with the four Greek elements, seen in "Nightmare in Red," prove to be vital clues to getting through the barriers.
Hot Dog Water is killed off-screen when Mystery Inc. hears gunshot fire from Pericles' Kriegstaffebots when she held Professor Pericles at ransom to allow time for them to go through the element of air door. She is also the third character in the series to be killed by Pericles, right after Ed Machine and Cassidy Williams.
Among the people who have been forced to excavate the caverns in search for the location of the vault there are Curator Vronsky, Randy Warsaw, Robert E. Howards, Gorgeous G, Blaine LeFranc, Dan Fluunk, Skipper SheltonÂ and Alice May.
In the beginning scene, Enrique pretends to be abducted by the Priestess, then dragged into the temple, where he presumably puts on the costume and emerges as the Priestess. But he would have no reason to do this, since no one else was around and Angie was only on the phone. This particular sequence appears to have be simply developed for the audience to discard him as a suspect.
The path of the plane over Texas towards Yucatan is another indication that the city of Crystal Cove is on the West coast.
One would think that Fred would've had already confronted his fake dad after the events of Wrath of the Krampus when he looked after the gang's pieces of the Planispheric Disk. This could possibly be explained by the fact that it might have been another member of the gang to ask Fred Jones Sr. for help, and not Fred himself.
Velma finds it hard to believe what is happening is real and needs cold, hard facts, and this has always been her way. Despite the fact that she already saw the real mummy of Friar Serra in "Theater of Doom" talking to her and the gang, and seems to forget that she didn't question whether the Wild Brood, from "The Wild Brood" or Amy the siren, from "The Siren's Song," were real or fake.
It is revealed that the Monstrous Freak is what inspired Fred Jones, Sr. to be the Freak of Crystal Cove first seen in "Pawn of Shadows" and revealed to be him in "All Fear The Freak."
The connection between Professor Kharon first seen in "The Devouring" (on the cover off his book) and the "dancing man" first seen in "Stand and Deliver" is established - they're the same person. The "dancing man" is the best part of him trapped from the time he spent in the sitting room.
According to Velma, she was never late for school before which seems unlikely even from the first episode in the series, where they were prevented from arriving on time by the Slime Monster who attacked the Mystery Machine.
The red room, 'other Nova', and the dancing, reverb voice ladenmidget that Scooby sees in his dreams are a reference to Twin Peaks. In that series, Cooper sees the little man, and another version of Laura Palmer, the girl whose murder he is investigating. The red room is the entryway to the Black Lodge.
This is the second time that Scooby and Shaggy saved the day, the first time was in the last episode "Dance of the Undead".
Francilee Jackson said her cornbread had been turned down, due to how she accidentally says her cornbread isn't made from real corn which we learned from "Web of the Dreamweaver".
This episode marks the second appearence of Dr. Rick Spartan, Cachinga and Francilee Jackson.
The music notes that mysteriously appeared on the Planispheric Disk and are also hum by the Hex Girls are based on the series main title music.
The girls explain that the reason why the are wearing their original costumes is because there was a public demand, meaning their costumes in the episode In Fear Of The Phantom are actually their second ones. They also wear two other outfits: the second is skull-like outfits based on the Dia de Los Muertos (Day of the Dead), that they wear to take on the zombiefied Rude Boy and the Ska-Tastics on a battle of the bands, and the last is more casual outfits.
Shaggy gives Scooby's name as "Scoobert Dooby-Doo" over the hospital intercom; Scooby's parents frequently addressed him by his full first name on the animated series A Pup Named Scooby-Doo.
When Scooby and Shaggy ask Thorn, Dusk and Luna to help them break the spell from Rude Boy and the Ska-Tastics, the girls are each wearing their original dress from their first appearance in Scooby-Doo and The Witch's Ghost.