Continuity mistake: When Shaggy and Scooby are performing the barber scene at the Coliseum, Shaggy is holding a sundial in his left hand and you can see that behind him there is a barber's chair, but when we see Shaggy holding the sundial in the next shot, the background has changed to a brick wall.
Continuity mistake: When Scooby grows back to his normal size after being tossed back into the Mystery Machine by the pizza man, he is initially sitting by Shaggy, but when Scrappy appears with his pizza in the next shot, Scooby is now sitting by the window.
Continuity mistake: When we see the pizza stand at the beginning, you can see there is nothing at the far end of the counter, but when Scrappy says "My uncle Scooby has all the fun", a wall with a poster has suddenly appeared.
Continuity mistake: When we see the pizza stand at the beginning, you can see there is nothing on the wall, but when the man takes Scooby and tosses him around, a "Pizza" sign has suddenly appeared.
Continuity mistake: When we see the pizza stand at the beginning, you can see there is nothing on the counter when the Mystery Machine drives past it. But when Scooby goes up to the stand, a plate of rolls and a napkin holder with two pots have appeared.
Continuity mistake: When Shaggy, Scooby and Scrappy have finished perming the lion's hair at the Coliseum, Scooby grabs Scrappy and sends the lion for a spin in his chair. In the next shot, the emperor says "Get off with the lion!" and he pulls a leaver releasing the trap door. But when we see saw the lion falling through the trap door, the barber's chair is nowhere to be seen.
Continuity mistake: When Scooby and Shaggy are at the "Hotus Dogus" stand in the Coliseum, you can see that Scooby has two flags in his left hand, but after a quick close-up of Scooby, we return to him and his flags have disappeared.
Other mistake: When Scooby is eating the hot dogs at the "Hotus Dogus" stand, his tail goes transparent.
