Holding the Guinness World Record title of Longest Running Science Fiction TV Series means "Doctor Who" has a lot of history. Maybe too much history. With 826 episodes — including the television specials — and counting, it would take an army of Whovian historians to sort out what happened when. Not to mention if the whens were still part of the current timeline!

So perhaps the show can be forgiven when things fall through the cracks. Fifty years of storytelling is bound to leave a few frayed threads of plot sticking out. Innocuous oddities like the First and Second regenerations of the Doctor only having one heart can be chalked up to the show still finding its legs (though if Moffat wanted to address it I don't think anyone would complain). But then there are plot holes so massive you could drive the interstellar cruise liner Titanic through them. Characters and situations so crucial it boggles the mind how they were ever allowed to fall by the wayside like so much detritus.

Below we've collected some of the most egregious oversights. The new season of "Doctor Who" premieres on BBC America on August 23. Perhaps a few of these lingering unanswered questions will finally have their day in the Gallifrey sun.