This was a good episode. But I did notice one thing and I am not sure if it has been mentioned.
The start of the episode has ted being asked to see the bride while he is in the room with Barney (groom). We see Ted walking to a door and ready to open it. No conversation with Marshal or anyone between the walk from Barneys room to the door about to be opened.
Flash forward to the end of the episode. Ted is talking to Marshal before going to this door and opening it to see Robin (bride) inside.
This seems good and fine BUT. The door Ted is about to open at the start of the episode is very clearly NOT the door he opened at the end of the episode. Simply compare the two shots and you will see the door at the start in a hall way with a turn in the hallway directly behind Ted. While at the end of the episode the door Ted opens is in a large room with a door (double door) in the background shot and no hallway.
So either this is some kind of mistake in shooting this episode or it could be something else. This can lead to so much guessing. Double wedding, final shot is from another time and not Barneys wedding, Robin went nuts and killed Quin and stole the dress?
All in all I would say that this episode was made to misdirect everyone first.
BTW - kids kill shows. I give it one last season before it is done for good. The moment Lily had the pregnancy on the show was the moment I knew it had one last season. Even TV writers know not to introduce kids in already popular shows.