Related Clues:

• Reason for a computer crash, maybe
• X marks this first in English, zero in the three Rs
• Mistake made by troublesome child forgetting time
• Panic, losing head? That’s a mistake
• Reason to say "Oopsie!"
• Wrong turn, e.g
• Catcher's interference is charged as one in baseball
• Code problem
• There's one in "beleive"
• There's one in 'beleive'
• Slipup
• “It is as certain as it is marvellous that truth and ____ come from one source” (Goethe)
• Wrong letter in a crossword, e.g
• Proofing catch
• Beta tester's catch