In Primeval, Giles calls Adam’s scheme “The Trojan Horse”. This was a famous military manoeuver in Greek mythology. The city of Troy was at war with the Greeks. The Greeks declared a truce and delivered the horse to the Trojans as a peace offering, but the Greeks had hidden thirty …

In Primeval, Spike says, “Alice heads back down the rabbit hole.” He’s referring to Lewis Carroll’s 1865 book Alice’s Adventures in Wonderland, about a girl named Alice who sees a rabbit in a waist-coat and follows him down a rabbit hole into a world named Wonderland.
The Angel episode Through The …

The four core Scoobies (Buffy, Giles, Xander and Willow) meet on campus at four compass points in Primeval. We see this recreated in the final episode Chosen, as the gang meet before they fight the First’s army.

“Whatever they think of you, it shouldn’t matter” - In Primeval, Anya reassures Xander (in her own quirky way) that she loves him. Their relationship lasts until Xander stands Anya up at the alter in Hell’s Bells.

In Primeval, Giles is hungover from his drinking binge in The Yoko Factor.

At some point between the episodes The Yoko Factor and Primeval, Cordelia rang Willow up for help cracking into a computer of her own to find files coded by Wolfram and Hart in Angel’s ‘Blind Date‘. In that episode Willow says “hey” to Wesley - a little in joke as …

Jeff Pruitt (Buffy’s stunt coordinator) and his wife Sophia Crawford (Buffy’s stunt double) left the show at the end of season four. His last huge fight sequence was in Primeval. This was apparently due to ‘creative differences’ with the production team. Jeff later went online to Buffy forums to air …

Spike tells Adam in The Yoko Factor that he killed two Slayers. We heard this first in School Hard, and see Spike relate his story to Buffy in Fool For Love.

Buffy and Willow’s phone in their dorm room keeps changing. In Living Conditions it was a white one with an answering machine, then it changed to a different design in Hush, and in The Yoko Factor, it’s a small, blue phone.

In The Yoko Factor, Giles seems to have been doing some redecorating. When Anya and Tara are in his bathroom, it’s different from how it was when Spike was chained up in it earlier in the season (Something Blue). It actually looks a lot like the bathroom from the house …

In The Yoko Factor, Willow asks Tara about housing for the following college year. The two end up living together in a dorm as Buffy moves home to be with her mother in season five.

In The Yoko Factor, Spike has a new TV in his crypt to replace the one Forrest broke in Goodbye, Iowa. He also has a video, a microwave and an old Nintendo - but no obvious sign of electricity.

In The Yoko Factor, Riley calls Angel “Mr. Billowy Coat King of Pain”. Angel’s long black coat billowing as he walks away mysteriously is a trademark of his.

The Buffy episode The Yoko Factor follows on from an episode of Angel called ‘Sanctuary‘, where Buffy turns up in L.A. to find Faith. She’s disgusted to find that Angel is helping her nemesis, despite what she did to Buffy. Angel and Buffy argue, and she leaves. He arrives in …

The following line of Spike’s was deleted from The Yoko Factor:
“Now that you’ve turned Super Wicca and you’re damn near Amish. All candles and hand-ground herbs…”