During the first part of the fight sequence with Buffy and April at the playground, Katrina is absent from the bench. She then reappears at the point where she regains consciousness and gets up off the bench.
When Giles shoves Spike against a bookcase in the Magic Box at 26:00, you can see Spike's reflection in the glass doors of the case.
When Buffy and Warren are carrying the unconscious Katrina over to the park bench you can see her legs moving as she walks with them instead of being limp.
As Warren talks on the phone with Katrina at 40:11, in the mirror above the fireplace behind him you can see the reflection of the boom microphone following him around as he moves. (Also, there are reflections of shapes in the background that may be crew members.)
When April tosses Spike across the room, the support wire can be clearly seen stretching out the back of his jacket.