Character mistake: Dr Smith who has some of The Robot (ie, bravery and courage) quotes The Fall of The Light Brigade but mistakenly says "into the valley death rode the five hundred" when it is actually 600. Both Dr Smith and the Robot would know this very famous poem's most well known line. (00:44:45)
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Suggested correction: There's nothing to suggest they would know the poem exactly, especially since you yourself don't even know the actual name of the poem. It's "The Charge of the Light Brigade."
The Night of Miguelito's Revenge - S4-E12
Character mistake: The store window's sign says, "Denver Mercatile" rather than "Mercantile."