This last "Episode" is so horrible, I'm reluctant to call it an "Episode." If you're in any way wondering if you'd be better off not watching it (except to see how bad it really is), you really shouldn't watch it. Many people criticize Season 5 and maybe Season 4 as being so bad that they're not worth watching. I think that's not fair to those seasons, but not hard enough on this last "episode".
People complain this ends with a "Cliffhanger", I wouldn't call it a cliffhanger, I would call it a "total train wreck."
At the end of Farscape, for example, they wrapped up everything in the local episode and the major arc's that were on people's minds, and then, at the last minute, adding in one last (big) problem that happened suddenly and then, when continued (by the TV movie) was wrapped up pretty quickly.
That "Fascape Cliffhander" is an example of what the end of this "episode" and the series wasn't. It didn't resolve any main arcs, it didn't even wrap up what I'm reluctant to call an "episode" it's failure to be "wrapped" up is the reason I'm reluctant to call it an episode in the first place, if we put aside the train-wreck/"cliffhanger" it was Part 1 of a multipart episode where the later parts were never made.
BTW... I've seen a lot of people are article discuss who should be blame for the loss of actors, especially Quinn ad Wade, but I haven't seen any put the blame where I think it belong - on FOX. Fox started a show that provided it could last five seasons (especially if they didn't Quinn and Wade). Fox should have put the main cast on 5-years contracts, and then run the show the 5 years. But regardless of what Fox secretly did with the contracts, it's no secret that the dumped the show after only 3 seasons (leaving Sci-Fi to pick up the mess - thank you Sci-fi.) The was also moved from Canada to Hollywood in Season 3, so that held so possible problems if the actors didn't want to move.
I've like to say more about the ending, but I don't want to make this review as "Spoiler" so I won't.
But I will finish by saying that after spend nearly over an hours think about whether or no there is any excuse for the "trainwreck at the end", I can only think of one.
When you continue a series with a made-for-TV movie, or a new series, the writers tend to try to like to "break everything" so the plot can put it together. The only good thing to say is that helped in that respect - they broke everything for the sake of the possible (but non-existent as of 2023) successors so they could hypothetically put it back together again. So, that the extent to which I can excuse or emphasis with it, which is really not-that-much.
Lastly, I want to say that I think an understated problem with how Season 4 and 5 "went off the tracks" is also often understated.
The main stated goal was "to find a way home", Season 1 through 3 treated the world shown in the pilot, sometimes referred to as "Earth Prime" or "Home" as the fiction version of the dimension we, the audience, live in.
Aside from the undesirable cast change, I think it was the extent to which the show moved the idea of the "Home" they were trying to return to further and further from the "Home" we identify with was a major cause of way people were became less increasing receptive to Season 4 and/or Season was they went on - even if many of those viewers don't realize it. But that's my opinion and my review of end of the show. Hope this helps.