On The Demo "Refrigerator":

The cassette was titled after the incident where following the murders of Leno and Rosemary LaBianca on August 10, 1969, Patricia Krenwinkel, a member of the infamous Manson Family, wrote the phrase "HEALTER SKELTER" (a misspelling of the title of the popular Beatles song) on the LaBianca's refrigerator using a blood-soaked piece of paper.

The version of "Dope Hat" that appears on Refrigerator is the exact same recording that is featured on The Family Jams Albeit, With a sound byte of Charles Manson as an Intro.

Tracks 1-4 can aslo be found on the Live as Hell Cassette.

In the credits section, the words, "Spread me open, stuck to my ribs, are all your infants in abortion cribs," would later be reworked into the song "Man That You Fear."

Contrary to popular belief. The Version of Thrift Found on Refrigerator and Live as Hell is not the same version from the unreleased Thrift (cassette) Demo
After School Special included the first official recording of "Lunchbox", albeit with a different chorus than the album version released on Marilyn Manson's debut album Portrait of an American Family in 1994.
After School Special also included the first official recording of "Cyclops", also slightly different from the album version released on Portrait of an American Family.
The lunchbox demo tape include the following (funny) line-up information:

Marilyn Manson - Vocals, Incantions
Daisy Berkowitz - Guitar, Drum Programs, Gun Repair
Gidget Gein - Bass, Guitar, Meats
Maddonna Wayne Gacy - Sampler, Keybored, Birtdays
From the "Lunchbox" Demo Tape:

A Lunchbox cassette surfaced on eBay on August 23, 2010.

Despite the cassette's title, the song "Lunchbox" was not featured in the track listing.

The two-color printed sleeve was printed for free by Daisy Berkowitz at his workplace.

The version of "My Monkey" that appears on Lunchbox is the exact same recording that is featured on Big Black Bus.

The version of Cake and Sodomy' that appears on Lunchbox is the exact same recording that is featured on Grist-o-Line.

The version of Dune Buggy' that appears on Lunchbox is the exact same recording that is featured on Grist-o-Line. With a re-recorded vocal track. The easiest way to tell the difference is to listen to the Charles Manson sample at the beginning. At the end of it, you can hear Marilyn Manson yell "beautiful."
"She's Not My Girlfriend" features the same riff as in "1996", a song from Marilyn Manson's 1996 album Antichrist Superstar, albeit played slower.
In 1991, a contest was held in which the first person to call the Spooky Kids Hotline with the correct answer to "What was the name of Willy Wonka's boat?" won a copy of the cassette Grist-o-Line demo.
The demo "Beaver Meat Cleaver Beat" was considered a "phantom" release, with even Daisy Berkowitz claiming in a 1999 interview not to recognize its title. In 1997 an original cassette copy, owned by Miami's alternative club DJ Hypno5ive the first copy discovered to exist was sold in an online auction. It was purchased by an anonymous collector in Japan, allegedly for over $1000.
The cover of The Beaver Meat Cleaver Beat is also believed to be a fake.
You can read more Here.
The only known owners of existing copies of the demo The Raw Boned Psalms are Manson's former girlfriend Missi Romero and ex-bassist Brian Tutunick (formerly known as Olivia Newton Bundy). The tape was first recognized after it was shown briefly in an interview with Brian Tutunick on the Demystifying the Devil DVD, released in 2000. You can read more Here.
In the demo "Big Black Bus":


On the side B of the tape, American heavy metal band Twisted Sister's "Come out and Play" can be heard in the background during Bill's message. American rapcore band Rage Against the Machine's "Wake Up" can be heard in the background during Elaina's message. Eight people left the band their home phone numbers.
Towards the end of the playback, an anonymous woman leaves a message saying, "Hey, when you come Wednesday night, bring me directions to the junkyard please. Okay, bye." It is speculated that this
message was left by Barb Warner, Marilyn Manson's mother.

Side 1" of the Big Black Bus cassette misspells "White Knuckles" as "White Knuckle".

The cassette was titled after the bus used by the infamous Manson Family in the 1960s.

The front cover of the cassette features the band's first use of the term "Holy Wood", where the words "HOLYWOOD PROD." can be seen on the side of the school bus. This term was used as the focal point of Marilyn Manson's 2000 album Holy Wood (In the Shadow of the Valley of Death) ten years later.

The title of the cassette is a parody of the Los Angeles bus operator Big Blue Bus.
The only known owners of existing copies of The Raw Boned Psalms are Manson's former girlfriend Missi Romero and ex-bassist Brian Tutunick (formerly known as Olivia Newton Bundy). The tape was first recognized after it was shown briefly in an interview with Brian Tutunick on the Demystifying the Devil DVD, released in 2000.
On the compilation "Lest We Forget":

The video for "(s)AINT" on the Japanese deluxe edition would be uncut if it were not for 2 seconds worth of material: at the 2:07 and 2:10- 2:11 in the video, it shows a vagina, and is blurred out due to Japanese laws, regarding nudity in video.

The DVD contains several easter eggs. There is a video of Manson's autopsy which can be found by highlighting his crotch in the special features menu. There is also the making of the "Mobscene" video (otherwise found on a limited edition single) and the performance version of the "Disposable Teens" video, which was shown on most television channels pre-watershed, because of the "disturbing" content in the original version.
In the album "Holy Wood", the disc contains a data track which leads to a video no longer hosted by Interscope's website. This video was later included as a secret track on the companion DVD of Lest We Forget
The central character of the album "Holy Wood" is its ill-fated protagonist "Adam Kadmon", a figure borrowed from the Kabbalah, in which manson described as the "Primal Man".
The album "Mechanical Animals" features a hidden, fifteenth track, playable only on a computer; it is untitled and experimental, further playing on the album's theme of the character Omēga and conformity. Upon entering the album into a computer, an autorun file starts a program that displays two of Manson's paintings while the song plays in the background. It is thought to be an experiment in synesthesia
"Smells Like Children" represents an era of the band full of drugs, abuses, tours, sound experiments, and is also a reference to the 1968 musical film Chitty Chitty Bang Bang.
Portrait of an American Family is notable for being the band's only studio album not to feature an image of Manson on the cover.
In the early stages of the album "Portrait Of An American Family", Manson intended to use a picture of himself as a child sitting nude on a couch in the album's interior artwork. Though no genitalia is shown in the picture, and it was taken by his own parents with no vulgar intent, the label rejected the idea on the grounds that it could constitute as child pornography, so Manson instead created the clay sculpture present on the final cover artwork of the album. However, Manson did eventually use a nude photo of himself as an adult for the inside flap photo for the CD single for "Lunchbox" but did not expose his genitals
The album Portrait Of An American Family's original cover art featured no text, simply a painting of a clown by John Wayne Gacy.