"Secret of the Ghost Rig" is the third episode of Scooby-Doo! Mystery Incorporated. It premiered on July 26, 2010.
- Frank Welker as Scooby-Doo, Fred, Barty Blake
- Mindy Cohn as Velma
- Grey Delisle as Daphne
- Matthew Lillard as Shaggy
- Lewis Black as Mr. E
- Gary Cole as Fred Jones, Sr., Motorcycle Cop
- Vivica A. Fox as Angel Dynamite
- John O'Hurley as Skipper Shelton
- Kath Soucie as Nan Blake
- James Arnold Taylor as George Avocados, Rung Ladderton, Teen Driver
- Patrick Warburton as Sheriff Stone
- The title card names the episode "The Secret of the Ghost Rig".
- When Daphne is sewing Fred's new ascot, she is humming the The New Scooby-Doo Movies theme song.
- During the final chase scene, the color of Fred's ascot switches from Rung Ladderton's purple one to Fred's usual one, several times back and forth.
- Mayor Jones tells the crowd the gang has recovered the missing diamond. However in "Theatre of Doom", it is revealed it was Burlington Library hidden the entire time.