During the season 2 finale A Canterlot Wedding, there are somethings that I was wondering. Like in the very beginning, before the show starts, the true Princess Cadence was kidnapped by the changelings so Chrysalis can impersonate her to feed Shining Armor's love and grow powerful. This might be an unknown threat that Canterlot was concerned of. But during part 2 of this finale, there was no flashback on how Cadence was trapped in the caves by Chrysalis.
There are some characters that I thought could have been added to this mix. Like Trixie who after season 1 was humiliated and rejected by other ponies because of Twilight. If not for Magic Duel in season 3, she would have returned in this finale as a temporary antagonist by joining forces with the changelings and help take over Equestria. She first acts like see learned something after Boast Busters and wants to start over with Twilight's friends, but it was later all a trick to help kidnapped the Mane 5 and Spike at the first ceremony. Also Zecora from the Everfree Forest who know stuff about magic, could have played a supporting role in the finale. If she appeared she might have tales or knowledge about the changelings other than Cadence(the real one), and also the name of the queen.
By combining these two paragraphs on top, they can make an interesting finale than what it has originally aired. I started with same scenes as it was, but the Mane 6 are shock to see Trixie again. Trixie seems to be "reformed" for now, and wants to help with the wedding. Not knowing that Chrysalis disguised as Cadence invited her to Canterlot so those two can put there plans into motion. After Twilight was turned against by her own brother, friends and mentor, Trixie was enjoying Twilight's devastation and watch her get sent underground from a far distance with an evil look in their face. In part 2 while Twilight and the beaten but real Princess Cadence are trying to escape to stop Chrysalis, they stumble not the hypnotized bridesmaids, but a portal that lead them out of Canterlot. It was possibly Trixie's plot to make sure they don't disrupt the plans or the wedding. While wondering in the Everfree Forest, the came across Zecora. And after a conversation about the changelings and how Cadence was captured by those creatures, they raced back to Canterlot with Zecora tagging along. Back at Canterlot, once the ceremony is near completion with Trixie possibly taking Twilight's place as best mare, Chrysalis reveals herself shocking every pony. Shining Armor is now under a trance. Trixie now took this opportunity to capture the Mane 5 and Spike. Princess Celestia tried to stop the queen, but she was overpowered and defeated miserably terrorfying the ponies even more. All of Twilight's friends felt very guilty and ashamed for not trusting Twilight and her deep concerns of something amiss. As soon as Trixie said, "No pony in Equestria will be able to stop us", Chrysalis proclaimed there is no "us" and told Trixie she is no longer of any use to the changelings and was prisoner with Twilight's friends leaving Trixie in a state of depression for being double crossed. During the invasion, Twilight, Cadence, and Zecora were soon captured and brought to the wedding hall she sees her friends, brother, and mentor in a lot of trouble. Chrysalis soon released the Mane 5 and Spike, except Trixie. After see how depressed and guilty Trixie is, she encouraged the queen to release her too, which she did. They soon apologized to Twilight for not trusting her. While Queen Chrysalis is preoccupied with the chaos outside with Canterlot under attack, Twilight encourages Cadence to go to Shining Armor to break the spell. After the Spell is broken, Cadence and Shining Armor combined their magic and sends Chrysalis and the changelings out of Canterlot. With peace being restored, Trixie wanted to apologize to everypony for betraying Equestria before she got tricked, but all was later forgiven and invited to the real wedding ceremony possibly as another bridesmaids, as for Zecora she was later been asked to attend, which she agrees. Once the preparations are done, the real wedding ceremony takes place. Celestia then congrats Twilight for her bravery and learned the lesson of trusting ones instincts. At the reception, Trixie is now being fully reformed and being accepted by the other ponies as they are partying along with Zecora. Season 2 ends like how it was in the original finale.
There are also still some things in my mind. I wonder where Princess Luna is when the invasion was taking place and not around to help her sister. Once the ponies became disappointed to Twilight for acussing others with out any evidence and rejected her, Twilight might face future punishments like being banished, or thrown in the dungeon, or thrown in a dungeon in a place that she is banished to. But once the changelings were defeated and possibly gone for good, Twilight may still carry the scars inside of that very incident where she lost the trust of her brother, friends, and teacher along with Chrysalis almost succeeding in ruling Equestria will possibly give Twilight nightmares in the future.