-The 3 dog heads is Cerberus, who in greek mythos prevents souls from leaving the Underworld and it's master is Hades/Shadowman?
-You can see a portal under one of the dog heads, that some people thought was hell, which could be the Underworld.
-The plane is called Icarus, after a guy who used wings to fly.
Just a fun thought i had and i wonder if there are any more nods to it. Then they brought the greek myths back in bo4.