Marcy & Hunson was just... good. Despite their seeming hate-indifference relationship they both instinctively seeked to protect each other in a moment of need, stuff like that is really nice to see, but at the end of the day, it's nothing new. The song sounded pretty cool, though with the lyrincs mentioning "other boys" as if the singer was male, I have to wonder is it just another cover? The humour worked pretty well here, and even Chicle blended nicely into the story and didn't distract from the main plot. Nice touch with Finn being the one to save Marcy & Hunson at the end, maybe sort of an excuse for his uselessness in Stakes. Also, seeing Olson absolutely kill it as HA, I wish he'd appear more. Overall, I really wanted the final Marceline episode to give us something truly great, but the result is fine too.
First Investigation is easily the best of the bunch. There's no real point here other than to remind us of a bond Finn and Jake share with Joshua and Margaret, yet the execution is absolutely fantastic, with a lot of cute and funny moments. Also I loved the overall atmosphere of spending a night in a spooky house the protags have childhood memories of. The overall theme of time travel and seemingly unconnected events influencing each other gave more substance to the plot points themselves. Thus, every plot point had an adequate ground instead of just being slapped together in the end like in RoF. Pretty creative explanation for the phenomena as well. The ending cliffhanger seems to hint that for the remaining 8 episodes, the series is gonna stop messing around and start finishing up on all the plots, or at least I really hope that's the case.