When Piper and Leo are in 1975 talking to Patty and Victor, Piper tells them about Phoebe and Paige being Patty's daughters, then she mentions the Power of Three, and Patty says, "That makes you the Charmed ones." This makes four daughters, and the prophesy only spoke of three sister witches. Patty doesn't ask about Prue, or ask how the four of them can be the Charmed ones until they change the past and Prue isn't there.
In Season 3, when Phoebe and Prue are talking about who is going to be Piper's maid of honor, and Phoebe tells Prue that she and Piper had bonding time before Phoebe was born. Prue responds "she was one and I was three." Yet in this episode Patty tells Piper that she is three and Prue is five, and Piper ends the sentences with "Phoebe isn't born yet."
The smoke that came from the blasted locket (which Piper blew up to open the front door of Phoebe's condo) does not act natural when Piper and Leo walk through it. It just fades away. It was digitally added.
In the first episode, we see a picture of Piper, Prue and Phoebe in this order. In this final episode (we do not see new pictures of the original Power of Three or the new one), we now see a picture of Piper, Paige and Phoebe, with Paige taking the spot of Prue. This can be seen as a tribute to the original picture from the first episode.
Why didn't Melinda travel back with Chris and Wyatt? If she inherited Piper's powers and was involved in the "family business" then it would have made sense for her to go back to the past with her older brothers to find out what happened to Wyatt's powers.
TRIVIA: Over the course of the series, a total of 610 evil beings are vanquished. The vast majority (466) are demons. 26 warlocks, 39 vampires, 18 darklighters, 11 mortals and 50 various others make up the rest. The Charmed Ones themselves account for 374 of the killings. Of the remainder, 23 are vanquished by Cole, 25 by Leo, 27 by Billie and Christy, 34 by other good guys and 127 by other baddies.
In the beginning of the episode, Leo tells Piper to "keep it down" when she blasts the door open. Yet, we have never seen her control the intensity of her blasting power before so how did he expect her to do it?
TRIVIA: In the end of season 6, Phoebe had her active powers taken away by the Tribunal. As of this episode, she only earned one of her powers back - premonition. It was never explained if Phoebe ever received her powers of levitation and empathy back, though she showed signs of her empathy powers in the season 7 episode Ordinary Witches.
When future Chris and Wyatt see Grams, Chris recognizes her. However, Wyatt does not. This clearly indicates that all future visits from Grams stopped after the final battle, so why did Chris recognize her? While we know that he met her during season 6, that Chris (the one from the dark future) died and was reborn into a different world where his life turned out different. Therefore, he should not have had any memory of any of that since the future changed and it never technically happened, meaning Chris, at least that one, never came back and should have had no more knowledge than Wyatt.
When Past Patty see present Victor she excitedly hugs him, oblivious of the future of their marriage, which Victor responds to by informing her of (with somewhat of an attitude). What exactly was Victor's problem anyway? The two of them have since resolved their issues in the episodes "Just Harried" and "Cheaper by the Coven," so why all the resentment in his voice?
When the girls and Billie go back and kill the Triad with potions, Piper blows up first Dumain from the future and then the one from the past, he is gone for good. But then when Billie kills Christy, it is Christy from the future that dies. The Christy from the past should be somewhere in Magic School with past Billie, which means she should be alive when the Charmed Ones return to the present. How did she die?
TRIVIA: Piper was the first and last sister to appear on screen on the series.
When Piper and Leo went back to see Grams, little Piper was clearly older than she was in the episode That 70's Episode, not to mention the fact that Patty had already passed, so not only should Grams know who adult Piper was, having met her only years before, but she should also know she is a Charmed One.
TRIVIA: With the ending of this episode all four of the sisters have seen or been their younger and older selves. Younger - Prue (That 70's Episode and Be Careful What You Witch For); Piper (That '70s Episode, A Witch in Time and Forever Charmed); Phoebe (The Three Faces of Phoebe and Hyde School Reunion); Paige (A Paige from the Past). Older - Prue (Morality Bites); Piper (Morality Bites and Forever Charmed); Phoebe (Morality Bites, The Three Faces of Phoebe, and Witchness Protection); Paige (Charrrrmed).
In the episode a special effect that plays with the whole travelling in time scene. It's the scene in Victor's house. Victor is sitting at a table with a drink and he's burned by the drink. Someone knocks on the door and he gets up to open it. It's Piper and Leo. Then the time is changed so that never happened and history keeps on. The same moment is shown - Victor is sitting at a table with a drink and he's burned by the drink. Someone knocks on the door and he gets up to open it. Now in the exact same moment that Piper and Leo get there in the past Wyatt, Chris and Patty get there. It's the exact same moment in the alternate future and the new one and the scene is the same one in both.
In the scene where Phoebe and Paige are asking how all that happened with Piper, Patty and Grams Coop appears. (Just before Chris and Wyatt had arrived from the future). When Coop appears he says to Piper: "Thanks for telling me she's not dead". Why would he say that? Time had been changed and he wouldn't know about that. Coop knows that Phoebe is dead when Piper gets to Victor's house and says it to Coop. When they changed time that moment never happened so Coop never would have known Phoebe was dead and he would have never said that to Piper, except for the possibility that Coop exists out of the timeline since it's his ring and he may be connected to it.
TRIVIA: Piper travels back to the same year that her self of 1998 did in the episode That 70's Episode. She arrives at the moment of Phoebe's conception, mere weeks before her self of 1998 would arrive, meaning Victor and Patty break up during those few weeks between both her arrivals. They only get back together because of Patty's pregnancy for Christmas as seen in the episode Thank You For Not Morphing, but they separate immediately after.
In this episode, Piper seemed surprised when she arrived in the future and saw future Piper and Leo and asked who they were. However she has already met future Leo in the episode The Jung and the Restless that aired earlier in the season and took place before this episode.
After Adult Wyatt gets his powers, he orbs to Piper's side to prove that he has gotten them back. A portion of the stained windows' frame in the sun room moves, behind Piper and Wyatt as Wyatt orbed.
TRIVIA: In this episode it's shown that witches can kill each other with their own powers - because Billie vanquished Christy with Christy's own fireball.