Memphis coach Dave Joerger said centre Kosta Koufos, forward Jon Leuer and guard Beno Udrih were sent back to the hotel to keep them away from their teammates.
A Grizzlies spokesman said he understood that Allen and Lee had both been hospitalized to receive fluids because both were dehydrated.
To fill out their roster, the Grizzlies signed guard Kalin Lucas and centre Hassan Whiteside from Iowa of the D-League. Both players were with the Grizzlies during the preseason but were waived before the regular season.
Lucas and Whiteside gave the Grizzlies 10 active players to face the Raptors.