When Daphne is sewing Fred's ascot, she hums the theme song from The New Scooby-Doo Movies (1972), Scooby's second TV series.
After the gang gets startled by the ghost rig in the cave, Scooby, Shaggy, and Velma cover themselves in the "See No Evil, Hear No Evil, Speak No Evil" position. Scooby covers his eyes, Shaggy covers his ears, and Velma covers her mouth.
When the Mystery Machine jumped over the ramp, it made the same sound effect that the Mach 5 does when it jumps over objects from the Speed Racer (1967) series, or "Speed Racer" in America.
The music when the Ghost Truck follows its victims is similar to the music from the Saw Franchise.