Sarah Michelle Gellar was away shooting the Angel episode ‘Sanctuary‘ during the filming of Where the Wild Things Are which is why we see so little of her in that episode.

James M. Connor played the Initiative scientist in Where the Wild Things Are, New Moon Rising and Restless. He played Jack in The Yard Sale, and was Randall’s Best Man in About Schmidt. He has also been in Gilmore Girls, Scrubs, The X Files, and The Drew Carey Show.

Danielle Pessis, who played Christie in Where the Wild Things Are, played Rachel in MTV’s Undressed and R.J. in Angel in Training.

Neil Daly played Mason in The I in Team and Where the Wild Things Are. He has also been in Brink and Flashpoint.

Kathryn Joosten, who played Genevieve Holt in Where the Wild Things Are, played Mrs. Landingham, secretary to the President (played by Martin Sheen) in The West Wing. She has appeared in Dharma and Greg, Becker, Ally McBeal, The X Files, Providence, Seinfeld, Charmed, Joan of Arcadia, Scrubs and Frasier. Kathryn …

We see in Superstar that Spike now has to buy blood from the butcher, just as Angel used to (such as in The Prom).

In Superstar, Jonathan mentions the clock tower and the gun, referring to the time he was going to kill himself before Buffy stopped him in Earshot.

When the world returns to normal in Superstar, one of the Jonathan posters on a wall changes into a poster of Oz’s band, Dingoes Ate My Baby.

In Superstar, Jonathan claims that Adam’s power source is a reservoir of uranium 235 in his chest. This information is actually true and helps Buffy to defeat her foe in Primeval.

In Superstar, Jonathan claims he was presented with the Class Protector award by Buffy, except he wasn’t really. Buffy got the award in The Prom - a sparkly toy umbrella.

In Superstar, when referring to Jonathan’s fame, Buffy says, “I’m not entirely sure that we can trust our memories”, which is a little reference to the fifth season, in which the Scoobies memories are changed to accommodate Dawn.

The movie Being Jonathan Levinson, mentioned in Superstar, is clearly based on Being John Malkovich.

In the credits for Superstar, Jonathan walking with his billowing coat is an obvious nod towards the Buffy spin-off show Angel.

Joss Whedon is a big fan of the movie The Matrix, and it’s been referenced in Buffy a few times. In Superstar, Jonathan claims to have starred in The Matrix. In Never Leave Me, the butcher calls Andrew “Neo” because of the long, black leather coat he’s wearing (Keanu Reeves’s …

The opening credits were redone temporarily in Superstar to include lots of Bond-style shots of Jonathan interspersed with those of the regulars. One shot, of Jonathan disabling a bomb, could be considered a parody of Xander’s bomb scene in The Zeppo. A few days before filming, Danny Strong was brought …