Related Clues:

• Slip
• It may be found in a proof
• Proof goof
• Typo
• Error
• Erratum
• Misstep
• Publisher's blunder
• Printing mistake
• ThiS, e.g.
• Key blunder
• Lapse
• Printing goof
• Tit for tat, maybe?
• There's one et 24-Across