In anticipation of buying the new Perez/Wolfman Teen Titans story, I am re-reading their classic Teen Titans run from the early '80s. In issue #19, they are battling Dr. Light and several animated Hindu statues. Those statues came from a museum exhibition that is managed by Carter Hall, aka Hawkman. Only he's the Hawkman of Earth-2 and shouldn't be randomly showing up in a Teen Titans story on Earth-1 without explanation.
So was this the same kind of mistake that was repeatedly made in Brave & the Bold, when Wildcat kept teaming up with Batman? Or was Carter Hall temporarily living and working on Earth-1? There was a brief reference in the story to him not getting along with Shiera due to something that happened in a recent issue of World's Finest, so maybe that story explains what Hall is doing on Earth-1.