Decades ago, ads touting merchandise at bargain prices often came equipped with a screaming headline: "This is not a misprint!" A Google search reveals that the phrase is still in use, though the word misprint has a somewhat archaic ring.
""This is a Misprint" New Funny Bloopers and Arch Ripostes,"
Word Ways: Vol. 47
, Article 12.
Available at: http://digitalcommons.butler.edu/wordways/vol47/iss1/12