When the fire sprinklers activate in the theatre lobby, all the sprinkler heads activate causing water to flow in all areas of the theatre. In reality most all fire sprinklers (except deluge systems) have sprinkler heads that activate individually through the build up of heat at each head causing a fusible link or frangible bulb to release a cap allowing water to flow.
Just before Angel bites the woman in the alleyway, she is seen smoking a cigarette. When Angel has bitten her, he exhales smoke. Smoke doesn't go to the bloodstream.
As the Judge is zapping his first victim on the stairs at the mall, the entire background scene of the mall below is frozen. This is especially noticeable in the case of a stooped-over man visible past the Judge's left elbow.
When Angel and Drusilla jump off the stairs to escape the explosion of the missile, their stunt doubles' faces are seen.
While Angel wears his claddagh ring the correct way, Buffy wears it wrong. Traditionally, the ring should be worn on the right hand facing out to show one is single and facing in to show one is taken, and on the left hand facing out to show engagement and facing in to show marriage. The way Buffy wears hers implies marriage. If claddagh rings come from Angel's people, he should know this.