Imagine you are watching or reading a work in which a certain amount of suspension of disbelief is required (such a work is typically science fiction or fantasy). And then, out of nowhere, comes this other plot device which cannot be a plot hole just by the sheer amount of thought that had to be put into it, but, nonetheless, actively counteracts the suspension of disbelief thus far achieved. Is there a term or adjective that describes such a device? These devices are distinctive in that they are frustrating because even granted the often remarkable postulates of the plot, they are still ridiculous or ask too much of the reader/viewer.
I'm sure many people have experienced this phenomenon and have been frustrated by it. Whenever I've experienced it among friends or family, we often quip at the person who points it out by saying "This is what you have a problem with?", or something of the like, and go on to point out the equally ridiculous or more ludicrous events that have happened or things that exist. Of course, this quip is in jest and everyone agrees that it's ridiculous, but we are unwilling to pause to discuss it, and it is easier to accept it and move on.
I have many examples of this type of device. Of the ones I have in mind that would be well-known are of the 'cop-out' flavor, or in highbrow terms deus ex machina. For example, the eagles in the Lord of the Rings. J.R.R. Tolkien requires us to suspend a lot of disbelief such as disbelief in elves, hobbits, dragons, etc. But then he invokes the use of the eagles to save the heroes on more than one occasion; and yet, they are not used to end the main conflict in the story.
There are many more examples of that flavor, but I'm asking for a more general term. At the risk of losing some readers but for the sake of another example, I was particularly confused by Karl Ruprecht Kroenen from Hellboy. First of all, Hellboy required the audience to accept the existence of demons, mutants, and Nazis that created a portal to hell. All that is fine and good, but then Karl shows up, who somehow achieved immortality for himself through genius, but nonetheless needs to 'wind himself up' like a common pocket-clock. As though a person with that amount of genius couldn't figure out how to automate that required function.
Any suggestions to describe this type of plot device are appreciated.