So Ewoks have an appetite for humans (as well as Wookies and even droids) and after the battle of Endor there would have been plenty of enemy combatants kicking around. The Ewoks were obviously scavenging Imperial gear, we see some Stormtrooper helmets being used as drums at the celebration, so do you think the Ewoks took some troopers or Imperial officers for the purposes of a meal? Okay, so I guess the Rebel Alliance probably has a thing for humane and ethical treatment of prisoners, so any surviving Imperials captured after the battle were probably sent to a transport that would take them to either a prison facility or whatever the Alliance does with their POWs. But what about Imperials killed during the battle? While the Alliance might believe in treating the dead with dignity, even enemy dead, it's still possible the Ewoks grabbed a few dead Imperials when the Rebels weren't looking and enjoyed them at the barbecue, right?