Continuity mistake: When Phoebe and Cupid visit the memory of Phoebe revealing she is a witch to Dex, past-Phoebe has her hands down by her sides, but then her left hand suddenly jumps to her purse strap. Not only that, but in the original episode ("Rewitched"), Phoebe's hand remained on her purse strap the entire time. (00:11:05)
Continuity mistake: Paige asks how The Source was previously vanquished, but she was there both times: when the original Source was vanquished, and again when they vanquished Cole. Also Phoebe wasn't actually there for the final vanquish of Cole, but was taken back by Cupid as if it was her memory.
Plot hole: When Piper goes back in time to save her sisters from dying and get rid of the Hollow, right after Leo describes it as "time catching up with itself" and the new reality Piper takes over her body. Yet in Season 5 Episode 7 "A Witch in Time", Piper goes back to keep Phoebe from saving her boyfriend but once Piper changes the past, the original Piper fades away and the new reality Piper stays.
Visible crew/equipment: At the start, Piper tells Billie she needs to be patient with Christie, and when Piper adds that if Billie needs anything they are just a call or an orb away, the pink tape mark can be seen on the floor at Billie's feet. (00:01:10)
Continuity mistake: After Antosis and the Imp Master are vanquished, in a following shot we see Phoebe wearing a robe and sitting on the bed, then we see her "Julie Bennett" reflection in the mirror, but notice that even though the style of the robe is the same, the colorful designs are quite different in the reflection. This happens again later when the sisters and Leo are seen in the mirror's reflection, as they undo the spell to reveal their true selves. (00:33:25)
Continuity mistake: After the opening credits, while Piper tries to persuade Paige to help with the speed dating at P3, in two shots facing the bed and in the shot facing the mirror showing the "Jaime and Jo Bennett" reflection, the lamp on the far side of the bed is turned on. When Leo is holding Chris he walks past the mirror, and in this reflection that lamp on the far side of the bed is turned off, but in the next shot facing the bed that lamp is on again. (00:04:55)
Revealing mistake: While Piper is trying to convince Paige to be at P3 for speed dating, Piper says, "I will resort to whatever I have to, besides you might actually meet someone you like," and after the quick shot of Paige, when it cuts to Leo holding Chris as he's standing in the doorway asking for baby Tylenol, the mirror's glass is green at the right side of the screen - for the special effects editing of the fake reflection. (00:04:40)
Other mistake: After Piper tells Phoebe to get to know Dex well and fast because it may be the one sign Phoebe can't ignore, Piper ends the family meeting. In the following overhead shot as Piper walks out we can see her reflection in the wall mirror and it shows her long dark brown hair, but the problem is the reflection should be showing the "Jenny Bennett" golden blonde hair instead. (00:05:05)