When Phoebe is standing in the mausoleum it's clear that there's writing on the grave behind her. Yet after her premonition she needs to wipe away dust to see the writing.
When Prue hangs up the phone after talking to Phoebe, the sound of a dial tone is heard before Phoebe pushes a button to hang up her phone. Cell phones do not have dial tones, and Phoebe would not have had to hang up, as the call would have automatically ended when Prue hung up.
When Piper is laying on the couch unconscious, Prue sits next to her, holds her hand and talks to her. Prue speaks for a minute, then says "I know you tried to tell me in the attic and I..." but Piper tried to tell Prue she needed help at P3 just after Piper became possessed, not when they were in the attic. Correction: Piper did try to tell Prue in the attic. She asked Prue to help her at P3, but in the attic she said she was dying.