Possible Clues:

• 'Oops!' prompter
• Prepare to admit first blunder
• A thousand, I wager, is an error
• Pale following motorway blunder
• It's wrong — it's wrong to be seized by force
• Same kit reused? That’s an oversight
• Mass, I bet, is a blunder
• Going beneath major artery, risk blunder
• It may be marked with an 'X'
• Silly makes it