The Frozen Donkey Wheel
The last third of every Lost season begins with an episode that sets up a clear mission. Open the hatch. Rescue Walt. Furthermore, from the flash forward reveal onward, key finale scenes were given highly publicized (in LOST nerd circles, anyway) code names that generated speculation on what crazy twist would close the year out. Imagine our excitement in "Cabin Fever" when island vanguard Locke was tasked with moving the entire rock to protect it from would-be conqueror Charles Widmore.
Then one of the secret scenes was designated as the frozen donkey. Mysterious! Now imagine our faces when the actual method of moving an entire island was revealed to be a frozen donkey wheel located in the catacombs of the island. A few more hours in the writers' room wouldn't have hurt here, guys.