In Xander’s dream in the episode Restless, the following dialogue occurs:
Xander: “You gotta have something. Gotta always be moving forward.”
Buffy: “Like a shark”.
This is a possible reference to Woody Allen’s 1977 film Annie Hall, in which Allen’s character, Alvy Singer, states: “A relationship, I think, is like a shark. …

In season seven’s First Date, just after Wood successfully asks Buffy out, we see him take out a knife which is in a bloody handkerchief. He then rubs it clean and puts it in his Rack ‘o’ Blades. However the blood is dried in the handkerchief and on the knife …

In Innocence, when Cordelia is looking in the book for information on the Judge we see her put the book back on the shelf sideways. Then when she and Xander start kissing, the book appears and disappears behind Cordelia in different shots.

In New Moon Rising, when Oz turns up at Willow’s room, Willow asks if he would like to come in, to which he replies “actually I’d like you to come outside.” A sly little reference to the theme of this episode perhaps?

In Buffy’s first dream sequence in Surprise, Drusilla stakes Angel in the heart from the back. He then reaches out to Buffy and dies. In Becoming (Part 2), Buffy stabs Angel in the heart - and he reaches out to her before dying.

In the film Johnson Family Vacation, the character Nicky is seen watching the Buffy episode Chosen.

In Showtime, as the Scoobies and potentials are watching the door being battered by the Turok-Han, you can clearly see a black cable attatched to the door, for the purpose of pulling the door off of its hinges when it is kicked in. It’s in shot for a quite a …

In This Year’s Girl, when the Scoobies are all at Giles’s flat, the phone rings. It’s a call for Buffy, and it’s someone telling Buffy that Faith has awakened and escaped from the hospital. Who was it? And how did they know Buffy was at Giles’ house? …

Willow laments in The I in Team that everybody’s getting spanked but her.A few episodes later in This Year’s Girl, Willow tells Tara that they will recon til nightfall, after which the ‘ritual hiding’ begins. Tara looks deeply worried when she hears these words.
Perhaps there’s something they’re not …

A special feature on disc three of the season six box set is a pre-season seven panel discussion with Joss and some crew/cast members. When asked for some information into the upcoming season seven, Joss says, “…getting back to the very first, uh, mission statement of the show…” Did Joss …

At the end of Never Leave Me when we see Spike being held over the seal, his positioning is not quite right.

When we see the camera angles from behind Spike, his position is not directly over the seal. From this position it looks to me as if it’s just …

In Beneath You, Willow says to Giles:

“Well, for starters, the Hellmouth’s getting all rumbly again. And now I know it’s got teeth. And are those literal teeth?”

You could say that they are literal teeth - in Chosen Buffy and the gang go into the Hellmouth and it is full of …

In Out of My Mind, Buffy says to Riley, “you are not going to die” to which he replies “I bet you say that to all the boys”. Buffy says something similar to Angel in Graduation Day (Part 2) when Angel has been poisoned by Faith. She tells Angel, …

In the episode Smashed, Jonathan shoots Rusty the museum security guard with a freeze ray. The gun and his arm are frozen solid by the blast. In the next shot, we see Jonathan and Andrew walk past Rusty - and Jonathan is clearly not holding the frozen gun anymore.

In Smashed, Amy and Willow have the following conversation:

Willow: “Don’t you want to go see your dad?”
Amy: “No. Can’t. Not yet. Too many questions.”
Willow: “About where you were?”
Amy: “No, about how I got there.”

This is a reference to The Witch, in which Amy went to live with her father after …