The dwarves from deep rock Galactic are part of the warhammer 40k universe.

On the American Dad theory, there is a long-running theory that Roger's ultimate goal is to replace all of humanity. The start of the show is just him, and then "learning" to put on disguises, but he's become more and more people over time, to the point where it is hard for almost everyone (except the Smiths, who he trusts) to know it is him.

It isn't inconsequential, but an interesting theory on whether the finale of American Dad will either be finding out that Roger IS everyone, or if Stan saving Roger actually saved humanity by allowing Roger to see humanity.

The Teletubbies are the Elois from HG Well's The Time Machine.

So Blade Runner, Alien, and Predator franchises are linked, but I also a believer that the Terminator franchise is linked into the same, shared universe. Obviously Terminator has many different endings depending at which film you look due to timey wimey shenanigans, but if you pick one of the ones that the war is averted (I pick T2 as the sequels are not my favorite), it kinda makes sense. In this universe Dutch is the special forces ace that is picked (probably unknowingly) to be the model for the T800.

Celery Man takes place in Pierce Brosnan's basement.

Chris Meloni's character in Happy is actually just Stabler. His whole backstory as a disgraced cop is essentially really him (I think they even show a picture of him right out of SVU) but he had to change his name for protection.

Char Aznable's wild shift in character between the end of Zeta and the beginning of Char's Counterattack can be directly pinned on Kamille Bidan's mental crippling at the end of Zeta and Haman Karm's actions in ZZ.

Char, who always had a rather strong protective streak, more or less pinned his hopes on Kamille as a key to the future. Instead he directly experienced the Newtype backlash of Kamille being mentally crippled, and subequently could no longer sense him. This convinced him that humanity was doomed to eternal conflict, unless it was forced to advance.

Still unable to get over his protective streak, Char then manages to extricate Mineva Lao Zabi, the last remaining Zabi and perhaps the only one who he doesn't actually seem to harbor any hatred towards, to Earth. But Haman just creates a double, which she uses to drag Neo Zeon into yet another war for personal power. This convinces Char he cannot trust the future to anyone else, even after protecting the ones he cares about.

Thus, we reach CCA with a Char who is fixedly convinced of both the need for forced human advancement, and that he alone must be that leader.

That Crocodile is Luffy's mom. Gender Bent by Emporio Ivankov's devil fruit power so he can hide his true identity.

Jonathan Coulton's the future soon and the Doubleclicks' lasers and feelings talk about the same characters from two different points of view.

I have no proof of this, but the artists are friends, so there is that.

Deku's quirk is having an extra bone in his pinky toe