The Plot Hole was originally intended to be Doug Walker as himself. Rob Walker re-wrote the scene so that The Plot Hole became it's own separate character.
When going over ground rules, the Nostalgia Critic states he won't review anything currently in theaters. He broke his own rule in 2015, because while Jurassic World (2015) was still in theaters, the Critic did a traditional review of the movie (though he substituted skits and reenactments for clips.)