The ending makes no sense. The archaeologists find the sarcophagus of King Tootincandy buried deep underground, and bring it up with ropes all around it. They open it and discover Shaggy Rogers and Scooby-Doo have somehow gotten inside and are pretending to take a nap in there as a joke.
Another explanation is that King Tootincandy is a historical double of Scooby-Doo (like the legendary Ascoobis in Scooby-Doo! in Where's My Mummy?), buried in suspended animation along with his favorite companion, the double of Shaggy Rogers. But since the Scooby figure has an "SD" tag and talks just like him, in English, and since almost everything in the sarcophagus is an anachronism (modern pillows, a teddy bear, and sleep masks exactly like the ones the duo worn on the plane), the first explanation is the simpler one. Minutes or hours could have passed between the panel where Shaggy is last seen and the panel in which the announcement of the discovery of the sarcophagus is made, allowing ample time for the two jokers to prepare their trick.
The absurdly non-Egyptian name "Tootincandy" plays off "Tutankhamun" and possibly also the lyrics of Bubblegum Bandit: "he's a rootin', tootin', candy lootin'... bubblegum bandit."