Its established that Anya has resumed being an Vengence Demon. Which means that if Buffy, Xander or Dawn had wished that Willow would return to normal. Or lose her ability to wield magic the whole crisis could have been resolved instantly.
As Willow's battle with Giles begins, blood from her nose (by a punch in the previous fight with Buffy) disappears and reappears repeatedly.
As Andrew and Jonathan ride in the cab of a truck, the reflection on the windshield suggests the truck is moving but the trees outside the window never move, indicating the truck is actually stationary.
At 1:16 you hear Willow say, "No," as she waves her hand, but her lips do not form the word until after her voice finishes speaking.
When Willow raises the Temple of Proserpexa on Kingman's bluff, there are two cables attached to the spire visible on the right side of the frame. (These were cropped out in the 4:3 aspect ratio in which it originally aired.)
After Xander says "They must have skedaddled. Those little weasels." and he nearly slips in the hole, you can see someone holding onto the belt loop on his pants.
As Willow brings up the temple on the bluff, you can see the cords holding the building up.
When Buffy and Dawn are underground and Buffy asks for Dawn's help to fight the dirt monsters, you can clearly see a crew member's hand holding onto one of the claws that Dawn is fighting.
When Buffy tries to attack Willow in the Magic Shop, a crew member is visible when Willow flings her back.
When Buffy tells Giles that it was her time to die, and she doesn't know why she was brought back, that another slayer would've just taken her place, this was incorrect. Buffy had been killed by The Master previously and was replaced by Kendra, and Faith replaced Kendra when Drusilla killer her, so Faith would have to die before another slayer was called forth. Buffy's death no longer figured into the chain of slayers.