The wild cards here are Burt (Mike O'Malley), Carole (Romy Rosemont), Leroy (Brian Stokes Mitchell), and Hiram (Jeff Goldblum). Setting aside that Burt has not been in Finn's life long enough to react so strongly, what plan might these four come up with? Carole is slowly getting on board with the marriage, and possibly Leroy, too, but Burt and Hiram are dead set against it. What will they do to try to stop the wedding? It would be very unlikely that they would come around this late in the game, and keep their mouths shut, barring something happening to change their mind. And there simply isn't time for that. But will whatever they do actually change Rachel and / or Finn's mind?
By the way, are we to assume that Hiram and Leroy have been at all of the New Directions' events, just unseen up til now? For their characters to be absent seems unlikely, and their attendance at Regionals really makes the hole left by them over the past two and a half years really felt. It is a big mistake to wait until now to bring them into the story, though it's too late to fix that. Thank goodness the course correction is happening now, but it feels a little too late.
As far as music goes, "On My Way" delivers pretty well, though most of the episode is lacking song. There is merely one performance outside of the Regionals contest, and that is Blaine's aforementioned number. While powerful in context, one gets the impression that it might not have stood so well on its own. Context does matter, though, so it gets a passing, but not spectacular, grade.
The Warblers are a bit of a let down while performing "Stand" and "Glad You Came" for their Regionals entry. The group is severely lacking strong leadership without Blaine this year. Sebastian is an interesting character, perhaps, but he pales in comparison on fronting the group. Neither song choice is particularly impressive or memorable, and it's a relief that the Warbler's third number is omitted.
The New Directions, of course, are much better. "Fly"/"I Believe I Can Fly" is a cool mash-up that features six different members of the glee club! The second song, "What Doesn't Kill You (Stronger)," is, as promised, for the Troubletones, with each of the three main New Directions girls in the group getting solo time. Though where did the others come from? They haven't been practicing with the New Directions. One would be forgiven for assuming that they had quit choir until they suddenly show up here.