Shay

Once More, With Feeling - S6-E7

Revealing mistake: During the song-and-dance number "They Got The Mustard Out", if you look closely at the dancers, the man in green to camera right of the second row is horribly out of step with the music, and with the rest of the group. The spell makes everyone dance far better than they naturally would (Tara loses the clumsiness she often displays, for example), so it is a mistake to have someone under the spell dancing so badly.

Shay

Hush - S4-E10

Revealing mistake: In the fight scene at the clock tower, the first time Riley is knocked to the ground he kicks one of the strait-jacket demons in the face - his foot misses, but the demon still reacts as if hit.

Shay

School Hard - S2-E3

Revealing mistake: When Spike is talking to the Anointed One for the first time, one of the henchmen tries to rush him from behind and Spike backhands him without even looking, but Spike's hand movements, the reaction of the henchman and the sound of the punch connecting on the audio track are all out of sync.

Shay

Enemies - S3-E17

Revealing mistake: Watch Xander's right leg as Angelus punches him onto the sidewalk - it bends the wrong way at the knee and flies up to his waist, showing that it's a dummy.

Shay

Enemies - S3-E17

Revealing mistake: After Faith brings Angelus back, when she goes to punch him and he blocks, the stuntman switch is very obvious - he's noticeably taller, has different hair and doesn't even seem to be wearing any vampire make-up.

Shay

Beauty And The Beasts - S3-E4

Revealing mistake: In the teaser of "Beauty And The Beasts", when Jeff is running through the woods, you can see in the top left corner of several shots a lamp being used to light the scene.

Shay

Crush - S5-E14

Revealing mistake: When the porter is dragged back onto the train at the start you can see (more obviously if you watch in slow motion) that there's absolutely nothing grabbing him, not even someone's shadow. (00:04:55)

Shay

Revelations - S3-E7

Revealing mistake: In 'Revelations' when Buffy and Faith are fighting, the kick Faith aims at Buffy's face right after she says 'We can work this out' very noticeably misses, but Buffy still reacts as though it landed. (00:36:15)

Shay

I Only Have Eyes For You - S2-E19

Revealing mistake: After Buffy has entered the wasp-filled school there's a shot of the others standing outside waiting for her. In the establishing long shot if you look closely you can see they used the same shot as earlier in the episode - Buffy is standing there with them. (00:34:10)

Shay

Faith, Hope And Trick - S3-E3

Revealing mistake: During Faith's fight outside the Bronze in 'Faith, Hope And Trick' when she stakes the vampire, if you watch carefully, you can see the rubber stake bending. (00:15:20)

Shay

Chosen - S7-E22

Revealing mistake: In the last episode, 'Chosen', Anya beheads two Ubervamps. The second time she swings the sword it very noticably doesn't go anywhere near the Ubervamp's neck, closer to its stomach.

Shay

The Dark Age - S2-E8

Revealing mistake: When Buffy and Giles are talking in the school in the final scene, the same extra (in a beige shirt and blue jeans) walks out of the room behind Buffy twice. (00:42:50)

Shay