Alyson Hannigan claimed that two versions were filmed of the scene where she and Cordelia discover the room full of bodies: a tamer version for American audiences and a bloodier one to be shown in Europe.
Originally, another sign of the impending apocalypse was going to be stones raining down on Sunnydale High. It was cut out due to budget costs.
The exchange between Buffy and Angel where he starts to tell her that he likes her dress, but she cuts him off saying "Yeah, yeah. It was a big hit with everyone." was added in production and not in the original script.
At 43:25 marks the beginning of many "Hero Walks" for both the Buffyverse and the Angelverse. This one has Buffy in the lead, of course, followed by Xander and Angel.