Quotes: Failsafe Failure

Sarge: Oh no! That last lightning bolt fused the detonator! There's no way to turn this thing off!
Simmons: Can you do it manually?
Sarge: Impossible. I specifically designed it so that I wouldn't be able to defuse it.
Grif: Why?
Sarge: In case I fell into the wrong hands, and was brainwashed to help the Blues.
Simmons: Nice thinking, sir.
Grif: You had to get just one last asskiss in before we die, didn't you?
Red vs. Blue Episode 43

There's a mawkishly overdramatic scene in which a character sacrifices himself by bravely detaching and blowing up the entire Metroid wing of the spaceship with him inside. We'll let slide for now the issue of why exactly he had to be inside it to do this, but Metroids show up later on ANYWAY, so he might as well have just stuck yellow and black tape over the door for all the good it did!

This is like having an emergency light that plugs into the wall! Or a parachute with a rope that's connected to the airplane!
SFDebris, "Learning Curve"

It seems the ship blew a plasma injector, and is now down to just four. Archer insists the ship can run on four injectors just fine, but Trip points out it can't run on three.

Okay, see what I mean about Starfleet sending them out to look like idiots? If something is that essential to the functioning of your ship, why would you not carry spares? Multiple spares, at that?
The Agony Booth on Star Trek: Enterprise, "A Night in Sickbay"

Note to self: When designing outer-space headquarters, do not allow personal living quarters to be shot off into space by a control that is outside the room.
Chris Sims on X-Men, "Sanctuary, Part 1"

The defense system is perfect, Mark. It'll even bury our mistakes.
Dr. Jeremy Stone after a nuclear bomb countdown has started, The Andromeda Strain

It's what you'd call a failsafe. Except he only got as far as the "fail" part.
Tobi, on Itachi Uchiha's attempt to keep Sasuke away from the speaker.

"Note: Need to implement this."
— The Hidden Valley Bunker Self-Destruct Terminal upon clicking "Cancel Self-Destruct Sequence", Fallout: New Vegas

(chaos is wreaking havoc in Ponyville)
Twilight Sparkle: Don't worry, everypony! I've learned a new failsafe spell that will fix everything!
(Her horn glows, and a wave of light surrounds Ponyville. When it fades... nothing happens.)
Twilight Sparkle: My failsafe spell... failed! Now what do we do?
Spike: Umm, give up?
My Little Pony: Friendship Is Magic, The Return of Harmony: Part 1

"At Starfleet, we put the 'fail' in failsafe!"
SF Debris, in his review of Star Trek: The Next Generation's "The Nth Degree"