Plot Hole

A plot hole, or plothole is a gap or inconsistency in a storyline that goes against the flow of logic established by the story’s plot, or constitutes a blatant omission of relevant information regarding the plot, sometimes even contradicting itself. These include such things as unlikely behaviour or actions of characters, illogical or impossible events, events happening for no apparent reason, or, statements or events that contradict earlier events in the storyline.

Source: Wikipedia