So, the more interesting question would actually be: What ISN'T part of Tommy Westphall's conjured multi-slash-metaverse? This kind of exercise could technically go on forever, seeing as even citing an integrated show or other cultural product in passing makes you part of that construct.
McDuffie's point stands. People just need to chill over continuities and reboots. These are things that aren't motivated by a love of the medium, they're motivated by cold, hard cash and audience or readership numbers. Marvel and DC will keep piling up Infinite Crises and 52s for as long as they please, until they hit the *one* setup that basically prints money.
Then fast-forward sixty years or so if they're still around by that point, and they realize they've made another tangled clusterfuck out of their respective universes and, well, BOOM. Universe Reset. Again.
As for intertextuality in-between universes, that's not too surprising, usually. Entities like Yoyodyne, Wolfram & Hart or Weyland-Yutani are usually cited as quick, meaningless nods from one show's creator to another.
A games-related example would be id Software and their constant mention of the Mixom and Moxim corporations. They've been cited in virtually every id game ever. Going by the Tommy Westphall theory, this means everything put out by John Carmack's team is part of the same continuity, and everything that's ever shot off from the Doom and Quake standards of the nineties would also count. So on top of Commander Keen and Duke Nukem 3D, you'd have to add Hexen, Heretic *and* from there, shift over to literature because Hexen references Lewis Carrol's Vorpal blade, which is canonically used to kill the Jabberwock...
Then you have to repeat the entire procedure starting from Carrol and the Jabberwock, and we started with id and its fictitious companies!
So... Yeah. That's pretty much an exercise in futility.