During the whole bar sequence at the beginning you can see Bret (Bret McKenzie) wearing a shirt with the rejected gift idea, the cross-stitch of Sally Rachel Blanchard, from episode 5.
Bret McKenzie played a Rivendell Elf in both the Lord of the Rings and Hobbit series. So, in " Frodo, don't wear the ring" he is paying homage to a movie series with which he was personally involved.