I freely admit that I made a mistake.

我爽快地承认我犯了错误。

《牛津词典》

I admit I made a mistake—but don't hold it against me.

我承认我做错了—但别因此而看不起我。

《牛津词典》

Chen did not dare a response. After a minute, he said, "I made a mistake."

小陈语塞了。过了一会，才说：“我错了。”

《新英汉大辞典》

Representative DON SHERWOOD (Republican, Pennsylvania): I made a mistake that nearly cost me the love of my wife, Carol, and our daughters.

NPR: YouTube Emerges as Political Tool in Campaigns

You know, I made a mistake, and at a certain time, it came time to pay for it, and I paid for it.

FORBES: Forget Oprah: James Frey Talks Truth With Big Think

"I made a mistake and I regret what happened, " he said.

WSJ: Gabriele Marcotti: The Handshake Unheard 'Round The World