These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Upon hearing of the show being renewed for two more series.
Usually with Abby and Connor getting a relationship upgrade of some sort, in episode 8 of Series 3 and the finale of Series 5 when Abby proposes to Connor and he accepted.
Hell Is That Noise - In the series 1 finale, the team carry an oscilloscope which can detect the high frequency calls made by the bat-like future predators. Whenever it starts to bleep, you know you're in trouble!
Any and all appearances of the future predators. They've done a very good job of avoiding Villain Decay, despite the fact that they're clearly not impossible to kill.
Pretty much any creature qualifies for either this or regular Nightmare Fuel for someone.
Ho Yay - Nick and Stephen are pretty well suited for this.
Helen plans to wipe out humanity before it starts.
Helen takes a flying leap over the Horizon earlier on, when she kills Nick, after he came back to rescue her from a burning building.
Narm: In the last episode, Matt says "Nothing can survive out there, except for those ugly freaks".
Matt's fight with the tree creeper in the Cretaceous was also pretty silly.
Seasonal Rot: Series 3, 4 and 5 tend to get pretty mixed reactions, with the two former series taking most of the blow.
The Scrappy - Matt (with a side order of Creator's Pet), half an hour into the first episode of the Revival and he already is hated by some for being a smug git. Then again, his background is both false and was created specifically to appeal to the ARC recruiters, so he's supposed to seem like a Creator's Pet.
Too Dumb to Live: A woman who raised a Smilodon and thought it'd think of her as its mother and thus wouldn't attack her. She was very wrong.
Ugly Cute: The baby future critters at the end of S1.
The end of Season 1, where Nick gets back from the past and finds Claudia has been Retgoned.
Even moreso Episode 3.3, where Nick is murdered.
What an Idiot: the Future Predator that Leek sends after Lester. Whilst Lester walks, confused, slowly, unaware, down an exposed pathway, it does nothing except make scary noises. This costs it its life.