if you think season 2 had filler episodes, at least they were a good story on their own.
season 3 had many more “filler” episodes… episode 301,302, were filler, 304,305 were partly filler, 310 was one big huge filler….
301 – Introduces the cast to Neverland, kills of Greg and Tamara, reveals Peter Pan, shows us Neal’s fate in FTL, etc.
302 – This was a huge character developing episode for Emma and started out the “Charming is poisoned” storyline. I’d agree that the Snowing flashback was fillerish, though at least it started off what we know as the Take Back the Kingdom storyline and we got to see Regina’s reaction to Snow waking up.
304 – I’ll argue it was partially filler in the sense that Rumple and Neal just went in one big circle. However, it did establish Rumple discovering that Neal was still alive and brought some development in their relationship. The Pied Piper Pan flashback, though, felt fillerish in the sense that it was mainly there to tease us with Rumple and Pan’s relationship.
305 – People might have their reasons for personally disliking this episode, but I’ll argue it wasn’t filler in the slightest. We actually got Hook’s backstory for why he became a pirate, it was a significant character developing episode for Hook, it somewhat resolved the dreamshade storyline with Charming, and it was a huge episode for CaptainSwan (personal opinions on shipping aside).
310 – This was mainly the build up for the Mid-Season finale. The Snowing flashback, though, I would agree was pretty pointless and basically filler. This episode would have benefited better from being totally present day with more screentime for Ariel, Eric and the Darlings. The Ariel and Eric reunion in particular was very rushed.