Episode 4.5 suffers the most if seen at a wrong time, because its story, both chronologically and narrative-wise, takes place between Episodes 4 and 5, with characters acting according to the story progress up until that point, which creates a jarring discrepancy if watched after the later episodes of the main plotline. The first half of the episode is dedicated to worldbuilding, which again, is pretty pointless after the main story is over. The second half provides some extra backstory for the character of Ridget, who also got her character arc resolved well before the finale of the series, in Episode 8. Overall, even if watched in the right order, this episode is just an inoffensive filler, providing nothing but an opportunity to see the cast do more stuff, 6/10.
Episode 13.5 is an immediate follow-up to the final episode of the series (narrative-wise, chronologically it’s a prequel) and is much more relevant to the plot progression. It provides some background on the cultist fleet, which is necessary for connecting the finale of the main series with the follow-up OVAs. It also explains the origin of the second flying squirrel that first appeared in Episode 12 and followed the protagonist ever since. The episode’s storyline of Kugel and Linaria compares and contrasts with the storyline of Ledo and Amy, so it isn’t a filler by any means, but it feels a bit rushed to really work well, 5/10.
