The definitive end of the series. The loss of John Ritter was a series killer, as he was irreplaceable. 
But adding David Spade was just wrong on every level.
Just Shoot Me? He's fine for that. Rules of Engagement? He's fine for that. But this show, no. He's the wrong type of comedy for a more grounded series than Shoot Me and Rules.
This is the episode where I fully stop watching in rewatches. 

@kyrat wrote:
Somewhere between "Darkling" (2 episodes back) and this episode, Kes apparently grows 2-3 years worth of hair? That made the time travel part even more confusing... I assumed she was starting at a more future point due to her much longer hair.

Or she just "let it grow" instead of regularly trimming it. What's "2-3 years worth of hair" to a species that only lives 9 years? Human hair growth speeds would be irrelevant to a non-human.

@Tinalessia wrote:
why is this a part 2? Doesn't tie in with last week's episode...

Part 1 was on the original Law & Order. It's a crossover.
https://www.tvmaze.com/episodes/3181179/law-order-24x19-play-with-fire-part-1

The "guardian angels" are just annoying. Unfortunately it's not a skippable episode like most throwaway holiday episodes.