In the two days it takes Matt and Cleo to walk to Phoenicia, a god of water washes Alex' sarcophagus ashore and plants a tree beneath it, which grows rapidly to surround and protect it. Its reputed beauty spreads "far and wide," reaching the ears of Queen Astarte who then has the tree dug up and planted in her inner garden. That's an awful lot for a mere two days (which audiences don't get to see, either) - let alone that nobody seems to've had a problem in transporting and keeping alive and attractive a tree that weighs in excess of 3,000 pounds.
In part one, Osiris' sarcophagus was to be built entirely of pure gold but then substituted by a common material of similar weight with gold plating. Still, at 3,000 pounds (not counting Alex's corpse inside), it should be much more than any two men can carry and should not float downstream sinking only two inches beneath the water's surface.
When Cleo speaks personally to Max Asher, she calls him "Asher" - usually a distancing or authoritative form of address - rather than "Max" or "Professor" or the like.