I'm guessing this is an "easter egg" in the Medal of Honor: Allied Assault game...
When escaping from Trondheim (where you destroy the Naxos prototype and sink one of the submarine U-boats), the last section of the mission starts with you in a vent duct. Well, you're not alone up there and a little ways ahead of you (and moving as fast as you move) is the elusive Trondheim Duct Vent Slug.