|This needs a stretch.|
The kids go back to their high school for the Central High Carnival, and run into their old science teacher Mr. McDabble, who has created a ruby laser that can cut through the hardest metal. But before too long, the ruby ends up missing, and the kids have to find out what happened.
Insert details here.
- Mr. McDabble (single appearance)
- Police officer (single appearance)
- Carnival goers (single appearance)(miscellaneous speaking)
- Peanut vendor (single appearance)
- Caramel vendor (single appearance)
- Snacks vendor (single appearance)
|Mr. McDabble||He wanted to close the exhibit early. The box he had was believed to had contained the ruby inside.|
|Jerry as the Carnival Clown||To steal the ruby from the laser.|
|Don Messick|| Scooby-Doo|
|Casey Kasem||Shaggy Rogers|
|Heather North||Daphne Blake|
|Vic Perrin||Mr. McDabble|
|Jack Angel|| Jerry|
The following credits are how they are seen on-screen (or as close as possible).
- Executive Producers: William Hanna and Joseph Barbera
- Producer: Art Scott
- Story Editor: Tom Ruegger
- Supervising Director: Ray Patterson
- Directors: Oscar Dufau, George Gordon, Carl Urbano, John Walker, Rudy Zamora
- Assistant Directors: Bob Goe, Bill Hutten, Tony Love, Don Lusk, Ann Tucker
- Story Direction: Jan Green, Alex Lovy, Lew Marshall, George Singer
- Recording Director: Gordon Hunt
- Animation Casting Director: Ginny McSwain
- Voices: Adrienne Alexander, Jack Angel, Ed Begley, Jr., Randy Bennett, Arthur Burghardt, Howard Caine, Phil Clarke, Henry Corden, Candace Craig, Brian Cummings, Jerry Dexter, Jeff Doucette, Cheri Eichen, Bernard Erhard, Ernest Harada, Joyce Jameson, Byron Kane, Casey Kasem, Phyllis Katz, Zale Kessler, Heather North, Larry Mann, Bill Martin, Mickie McGowan, Joe Medalis, Don Messick, Michael Mish, John Paragon, Vic Perrin, Henry Polic II, Tony Pope, Neilson Ross, Michael Rye, Marilyn Schreffler, Marla Scott, Michael Sheehan, Hal Smith, Tony Smyles, John Stephenson, Andre Stojka, Jean Vander Pyl, Janet Waldo, Vernee Watson, Peggy Webber, Lennie Weinrib, Jimmy Weldon, Noni White, Alan Young, Marian Zajac
- Title Design: Bill Perez
- Graphics: Iraj Paran, Tom Wogatzke
- Musical Director: Hoyt Curtin
- Musical Supervisor: Paul DeKorte
- Creative Producer: Iwao Takamoto
- Design Supervisor: Bob Singer
- Character Design: Flor Dery, Jim Stenstrum, Lew Ott, Alice Hamm, Jean Gilmore, Mel Keefer, Gabriel Hoyos
- Layout: Charlie Grosvenor
- Key Layout: Terry Lee Keil
- Layout: Tom Coppola, Andrew Gentle, Carol Holman, Terry Hudson, Raymond Jacobs, Karenia Kaminski, M. Mike Kawaguchi, Ken Landau, Greg Martin, Alex McCrae, Jim Mueller, David O'Day, Michael O'Mara, Linda Rowley
- Animation Supervisors: Don Patterson, Jay Sarbry, Roger Chiasson, Sean Newton, Don Spencer
- Animation: Robert Alavarez, Frank Andrina, Tom Barnes, Bob Bemiller, Lefty Callahan, Rudy Cataldi, Daniel De La Vega, Joan Drake, Jim Duffy, David Feiss, Hugh Fraser, Jeff Hall, Bill Hutten, Ken Kessel, Bob Kirk, Rick Leon, Hicks Lokey, Ernesto Lopez, Ed Love, Tony Love, Ken Muse, Ron Myrick, Margaret Nichols, Kevin Petrilak, Virgil Ross, Bob Shellhorn, Ken Southworth, Tim Walker, Alan Wilzbach
- Assistant Animation Supervisor: Joanna Romersa
- Background Supervisor: Al Gmuer
- Backgrounds: Lorraine Andrina, Fernando Arce, Robert Gentle, Martin Forte, Jonathon Goley, Bonnie Goodknight, Phil Lewis, Andrew Phillipson, Bill Proctor, Ron Roesch, Gloria Wood
- Checking And Scene Planning: Paul B. Strickland
- Xerography: Star Wirth
- Ink And Paint Supervisor: Alison Victory
- Sound Direction: Alvy Dorman, Phil Flad
- Technical Supervisor: Jerry Mills
- Camera: Bob Marples, Bob Cohen, Steve Altman, Curtis Hall, Ralph Migliori, Joe Ponticelle, Jerry Whittington, Roy H. Wade
- Supervising Film Editor: Larry C. Cowan
- Dubbing Supervisor: Pat Foley
- Music Editor: Cecil Broughton
- Effects Editors: Jon Johnson, Carol Lewis
- Show Editor: Gil Iverson
- Negative Consultant: William E. BeBoer
- Post Production Supervisor: Joed Eaton
- Production Coordinator: Peter Aires
- Production Manager: James Wang
- Production Assistant: Robin Carmichael
- Executives In Charge Of Production: Jayne Barbera, Jean MacCurdy
- Supervising Executive: Margaret Loesch
- A Hanna-Barbera Production
- "Scooby-Doo" and "Scrappy-Doo" ©1983 Hanna-Barbera Productions, Inc.
- Hanna-Barbera Productions
- This episode reveals the name of a high school (Central High) that Shaggy Rogers and Daphne Blake went to for at least a portion of their high-school years. It also implies that Shaggy was probably not a good student.
Animation mistakes and/or technical glitches
- When the gang returns to the Science Exhbit to look for clues and get closer to the laser, they say the ruby is gone, although it was there the whole time, even when they run away from the shadowy figure who turned out to be the policeman.
- Right after this, the policeman turned his flashlight on the ruby's place and it was gone, but his flashlight was dark, while the rest of the tent was glowing.
Inconsistencies/continuity errors and/or goofs/oddities
- For no apparent reason Mr. McDabble gives a sinister laugh when picking up the ruby. This appears to be simply for the audience to have a suspect.
- It would be possible to put a mirror across the center of a circular dunk tank so that someone looking in from the correct angle would think they saw the back when they only saw the front reflected, but the mirror can be no taller than the lip of the tank. The mirror shown in the flashback is too tall for this to work.
- Scooby-Doo! and the Creepy Carnival DVD released on October 23, 2012.