Corrected entry: When Tara got shot, the hole in the window and Tara shows that the bullet has to have entered in a straight line, but Tara and Willow were on the second level and Warren was on the bottom level, and he shot upwards, not straight, so the bullet couldn't have entered in a straight line.
Corrected entry: During Buffy's training montage, she is seen punching a bag with her wrists bent. First, that's going to be a weak punch, super strength or no, because she can't transfer the force from her arm and body; it just bends at the joint. Second, that's a great way to injure your wrist, because all that escaping force snaps the bend farther. You could strain or even break the joint. After six years, Buffy should know better.
Corrected entry: Buffy is going to confess to the police and Spike is trying to stop her, so Buffy is punching him repeatedly in the face. We cut to Spike who is bleeding from his nose, which is all well and good. But then we cut to Buffy and she says, "I will never be your girl," and then it cuts back to Spike, he now has a huge cut over his left cheek that wasn't there before.
Corrected entry: In the episode 'Once More, With Feeling', during Giles' song, 'Standing', Buffy's hair is loose as we see her training montage. When she walks up to him at the end and starts to speak, she's taking it out of a bun. She's definitely not just playing with her hair - if you watch carefully you can see that there's a clip or pin of some sort in her hand that had been holding her hair up.
Corrected entry: When Buffy sees the news report about the frozen security guard, the reporter says that he is in critical but stable condition. In the next scene, Buffy sees the frozen guard being removed from the museum. How did they determine his condition without taking him to the hospital?
Corrected entry: Near the end of the episode they are fighting the vampires in the front lawn of a house. Buffy breaks the pole off a mailbox and uses it to stake a vampire. In the shot where she broke it off the ends are uneven, but in the very next shot one end has a point like a stake.
Corrected entry: Xander is visited by what he believes is himself from the future. We later find out it is a demon that used to be a man, but Anya had changed him back in her demon days. But when Giles destroyed Anya's pendant in 'The Wish,' it supposedly reverted all of her previous spells, which should have made him human again.