Joy spending 4yrs in the 1880s, and a photo of her taken back then surviving to modern day. Finding out more about Royal's background. Finally having true confirmation that Autumn is actually Amy.
There were also some bits I'm really curious about -
The time travel mechanics of the show. We don't seem to see paradoxes; prime example being Perry's actions in the last episode when he returns to the modern era, which results in the death of the slightly younger version of him. At that point, the older version of Perry who is still there should cease to exist - but he doesn't. So is this a new timeline? Or are people who've travelled through the hole somehow immune to temporal causality? We see something similar after Joy's presence in the 1880s leads to the situation where Perry shoots his father to save her. These events are not how he remembers things (he remembers aiming for a moving animal and accidentally shooting his father), but it's like he starts to absorb the memories of a new timeline and can now remember both of them occurring.
Also curious about Wayne Tillerson talking to the hole in the last episode, and it seemingly responding to him. This suggests the hole may not just be a naturally occurring phenomena but that's there's some kind of intelligence behind it.