Just wanted to drop this wiki quote in here...
"A plot hole is a gap or inconsistency in a storyline that creates a paradox in the story that cannot be reconciled with any explanation. These include such things as illogical or impossible events, and statements or events that contradict earlier events in the storyline"
...so we can clear away some of the proverbial wheat from the proverbial chaff in this debate.
For example...
Rox64 said:
Another rare thing: what's the hole where the rebel fighters infiltrate the Death Star? That whole hole in the middle of the surface. What's its purpose?
...is something that isn't explained because it doesn't require explanation. Not something that "cannot be reconciled with any explanation". So it's not a plothole... or even a flaw either, although it could possibly fall into the category "could-have-been-done-better" on some abstract level.