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.
Fridge Brilliance: Neo Getter-1 gets a new weapon (a machinegun) seemingly out of nowhere for Reversal, until you remember episode 2 of the OVA, where Professor Shikishima shows off a machinegun and mutters to himself about making a scaled-up version for the Getter.
She's Just Hiding: In Original Generations, Fiona Gureden delivers some sort of "farewell" death speech to her brother and friends in the prologue scenarios, making it apparent she may bite the dust (moreso than Lamia Loveless in the "2.5" bonus segments). It takes one trailer for Original Generation Gaiden to ruin the suspense, hence the lack of spoilers.