So to start off the second act of
Glass, two of the main characters (David Dunn and Kevin Wendell Crumb) are taken to a mental institution and kept under high security by Dr. Ellie Staple.
David’s cell meanwhile is made of steel and is equipped with 46 high powered nozzles that will spray David with water if he tries to escape. David’s commitment to the mental institution raises an important question, why is he here? As far as the greater world is known, “The Overseer” is nothing more than a vigilante, which is not necessarily grounds for being locked up into a mental asylum. The penalty for vigilantism is that of the crime you commit. Based on what is presented in the film, all of David's crimes are that of a misdemeanor, which if proven guilty of is no more than a year of jail. The reason we are given for why Kevin and David are both in the mental ward is because they think they have super powers. Now based on the way many of Kevin’s identities speak about the Beast quite often and taking into account that Kevin does have an actual mental disorder, it is logical he’d be taken to a mental facility. David on the other hand, not so much. He makes no such proclamations at any point leading up to this. At this point of the film all he hasn't spoken at all. When he does eventually speak it is to plead to be released so he can continue his vigilantism. Per the information we are currently given it makes no logical sense for him to be here, thus creating a plot hole. By definition a
plot hole is a measure of bad writing as it is an error in the plot. But is this an actual plot hole? No. The film eventually explains that there is a secret organization Dr. Staple works for that is bankrolling this whole imprisonment and were directly targeting David. This explanation fills in the hole resulting in a scene that is no longer poorly written. This portion of the scene would be considered good writing.
There is more to this scene though. As it progresses we learn that David's cell has water pipes installed. Why? Dr. Staple states that it's because water is David’s weakness. Why does Dr. Staple believe David thinks water is his weakness? She says it’s because she saw him choke up water after a fire hydrant exploded, but that’s not enough to assume water is his kryptonite. All people react to being suffocated to water the same way. To choke up water would be a natural. That was the point of it being his weakness in
Unbreakable, it was something he latched onto to help believe he was normal like most people. Why is your first assumption that it’s his kryptonite? That’s really convenient. It's not bad writing as it doesn't contradict anything, but one could argue it is weak writing. Even if there was solid reasoning for her to think that, why are they still there? Her whole plan is to convince him that he isn’t a superhero. Why are you then trapping him in a room that would release that said weakness on him if he tried to escape? This would only reinforce his belief of being a superhero. This is choice is inconsistent with Dr. Staple's character and motivations, making it a plot hole. Are there ways to fill this plot hole? Yes. As stated being hosed with water is something that would affect all people the same. By omitting the knowledge that she knows it's his weakness, you fill this hole of why she chose it and instead it would be convenience. The film doesn't present it as such though so instead this error is present throughout.
So now we have two examples of writing, the question remains of how do we weigh them. Well, we're talking about plot and plot holes, so the question becomes how much do these plot holes affect the plot? Which is more important to the overall plot? David being imprisoned is the inciting event of the film, if he is here for no reason then the rest of the plot's foundation is bad. Leaving the water pipe incident as is affects the logics of Dr. Staple's plan, but it does not change any of the film's following events. She still manages to convince David he might not be a superhero anyway, so this detail is inconsequential. If you were to tally it up, the good writing would outweigh the bad writing. Put this scene on a scale it would lean more towards the good side.