As Pike is driving his van with Amilyn holding onto the hood, the position of Amilyn's right hand switches back and forth from the roof to the hood between shots.
After Pike talks to Buffy while on his motorcycle, he does a turn toward the photo booth. You see a close up of him just as he his revving up his bike, and he is maybe two to three feet from the photo booth, which is not enough room to do the maneuver. In the next shot, you then see him about six or seven feet from the booth, and he does the maneuver.
When Benny is floating outside Pike's window, his reflection is visible.
When Amilyn is on top of Pike's blue van you can see the handles that the stunt man is holding onto in several of the shots as they are driving through the woods.
Benny can be seen already having fangs before he's turned into a vampire.
Wires are visible when Robert Berman flies up out of his grave for the first time.
After Buffy punches Merrick, she gives her "marry Christian Slater and die" speech. The reverse angle of Merrick shows Buffy's lips still moving, even though no dialogue is heard.
During the cemetery scene with Buffy and Merrick you hear a loon calling on more than one occasion. A loon would be on a lake, not in a cemetery. They can barely walk on land, and they only take part in calling during the morning and evening hours, never late at night.
When Merrick takes Buffy to the graveyard he shows her Robert Berman's grave and says he was buried 3 days ago. Yet the grave already bears a carved tombstone which would not have been possible in such a short time.
After the opening titles, Buffy and her friends are shown at the mall in an overhead shot and the boom mic casts a shadow on the floor.