The Ghost of Dead Justice's bullets from Scooby-Doo! Mystery Incorporated's "Dead Justice" have a striking similarity to Bullet Bill from Super Mario.

Thanks to Shadowscooby for suggesting this fun fact!

The announcer for the Globetrotters game in "The Mystery of Haunted Island" (from The New Scooby-Doo Movies) is not just a one-off character created for that episode. He appears in other episodes of the Harlem Globetrotters cartoon from the 1970s. In addition, the Laff-a-Lympics narrator's voice sounds exactly the same as the announcer in this episode, perhaps prompting an in-universe question of if it's the same announcer.

During the voice recording process for Scooby-Doo on Zombie Island, Frank Welker stated in an interview that he thought he might be replaced due to WB executives claiming his voice had gone down an octave since he last voiced Fred in 1984. Here's a quote from Welker on the matter from an interview with Animation Magazine.

"Coincidentally, when we were doing the direct-to-video movie, Scooby Doo on Zombie Island, I was basically the only one left from the original group. I thought they might replace me because they thought my voice had gone down an octave. I personally feel I can do Freddie right up front. When we were recording it, the director kept saying, 'Higher and higher,' and I kept saying, 'No, no, I don't think so. I did that for a lot of years,' and I went back and looked at some tapes, just to make sure, because I don't want to be doing something that would be wrong for the studio, either. And so they were looking at some old tapes, 'cause they were worried about some of the old voices and matching them. She [the voice director] listened to the Freddie voice and she said, 'I'll be darned. He's absolutely right. He sounds exactly like Freddie.' It's a double-edged sword."

Animation Magazine cited Cartoon Network's speeding up of episodes as a likely reason. To allow time for more commercials, the Where Are You reruns that were so popular in the 1990s had the animation and audio tracks slightly sped-up to make time for more commercials. It was a popular phenomenon at the time for Cartoon Network to time-compress the episodes by playing them at 1.05x or 1.1x speed. As a result, the characters' voices sound slightly higher-pitched than normal, which could potentially be why the WB executives believed Welker's voice had gone down an octave.

Surprisingly, there were no Scooby-Doo comics at all for a period of 17 years, between 1978 and 1995. There were a few reprints of Charleton comics in 1992, but there was no new content during this period. 

Another fun fact you may not know about the comics is that even before Scooby began frequently running into real monsters in the 1980s TV shows and films, Scooby ran into real supernatural threats quite a few times in the 1970s comics.

Thanks to Tom Holste for coming up with the idea for this week's fun fact!

Between all the promotions with food products, toys, Wendy's, LEGO, and even 1-800-COLLECT, Scooby-Doo on Zombie Island had the largest marketing campaign of Warner Brothers Family Entertainment's history at the time of release in 1998. Even Nascar joined in on the fun by having the #9 racer at the time, Jerry Nadeau, have his car painted with a promotional image from Scooby-Doo on Zombie Island at the 1998 NASCAR Winston Cup on September 12, 1998. Scooby-Doo Another surprising promotional tactic is that according to an AWN article from 1998, Scooby fans were treated to a live chat on AOL with an animated version of Shaggy and Scooby.

The controversy over whether the Ship Captain is one of the 13 ghosts is well known, since it's never explicitly stated in the episode whether he is one of the demons from the chest. However, one interesting fact I observed upon rewatching the series is that Vincent and the other main characters never mention Rankor by name at any point in the episode, or even acknowledge him for that matter (with the exception of the end scene when they put him in the chest, and when Vincent is turned to stone).

Prior to Scooby-Doo! Mystery Incorporated's "Mystery Solvers Club State Finals," many Scooby-Doo fans wanted Scooby to crossover with more clones than just Josie and the Pussycats. However, what a lot of Scooby fans don't realize is that there was a crossover with Captain Caveman in the 1970s! Despite not being advertised at all on the cover, Marvel Comics' Scooby-Doo #9 featured a crossover with Captain Caveman and the Teen Angels.

Thanks to Tom Holste for coming up with the idea for this fun fact, and providing these images!

Laurel and Hardy were already both deceased before "The Ghost of Bigfoot" from The New Scooby-Doo Movies aired. These were the only two celebrity guest stars in the franchise that had passed away prior to their episode being written and produced. (The Ghost of Abraham Lincoln was a historical figure instead of a celebrity, so I'm not including him here).

It's perhaps worth noting that a few guest stars also passed away shortly after their episodes aired. Both Larry and Moe of the Three Stooges both passed away in 1975, three years after their episode aired. Cass Elliot passed away in 1974, two years after her episode aired. Alex Trebek died after the production process on "Total Jeopardy!" had already finished, but before the episode aired.

While exploring an idea for another potential article, someone sent me a link that shared a bunch of examples of real-life Scooby-Doo hoaxes where people dressed up as fake monsters. I thought this was such a cool concept that I'd never explored before, so I wanted to highlight some of the most interesting examples. Obviously this isn't an exhaustive list of every instance in the world where someone has tried to pull off a Scooby-Doo like hoax, but I pulled out the most interesting ones that I found and wanted to share them with you all.

As far back as the 1200s, a castle near modern Luxembourg was abandoned due to legends of it being haunted by sinister sounds and eerie lights. King Louis IX hired some Carthusian monks to rid the place of ghosts, but the monks reported back that the "hauntings" were nothing but a group of criminals trying to scare people away from their hideout.

In 1926, an ape-man was sighted  on an old farm in North Stonington, Connecticut. Two young girls had recently inherited the farm from their father who tragically passed away. The neighbors theorized that someone was trying to scare the young girls into selling their father's farm, and planned a stakeout to catch the ape-man. It was then discovered that the girls themselves were the ones who created the ape man legend. They created a homemade ape man suit, because they were being pestered by solicitors. The girls wanted to scare the solicitors into thinking the place was unsellable due to being haunted.

In a similar case, Ray Wallace was the boss of a logging crew who was the first person to ever sight Bigfoot's footprints in 1958. After Ray died, the Wallace family divulged that Ray actually faked the whole thing in hopes of scaring away hooligans who were pranking his work vehicle.

Ivan T. Sanderson, a private investigator, uncovered some evidence that the Jersey Devil of 1909 was actually just real estate developers who dressed up to incentivize people to sell their properties by tricking them.

During the Vietnam War, the US used an exercise called Operation Wandering Soul to scare away their enemies. The US Military used tape recordings of eerie moaning and creepy voices to weaken their enemy's morale. The tactic saw varied success. Sometimes the enemy would be frightened away, but other times, the enemy would quickly realize it was a recording and attack anyway.

A British ghost hunter was called by a hotel owner to investigate a haunting. The ghost hunter found no signs of anything, but the hotel owner begged him to just "make up a haunting" because he felt the image of owning a haunted hotel would drive up business.

A Nancy Drew book from 1957 called The Haunted Showboat has an extremely similar premise as The New Scooby-Doo Movies episode "The Haunted Showboat" from 1973.  Nancy Drew #35 follows Nancy and her friends solving the mystery of a haunted showboat. The showboat is being renovated for a big gala event, but a ghost attempts to stop the event. Without providing any spoilers, the culprit's motivation also involves making money illegally as it does in the Scooby-Doo episode.