I am afraid that I have made a mistake.

我担心自己犯了一个错误。

youdao

I have made a mistake.

我已经犯了一个错误。

youdao

I recognize that I have made a mistake.

我认识到我犯了一个错误。

youdao

I must have made a mistake on my project.

我肯定在项目里出什么差错了。

Must 课堂 - SpeakingMax英语口语达人

I'm not going to have a go at Willie Collum, I think he's a smashing referee, but he's made a mistake.

BBC: Hamilton manager Billy Reid

"I have made a mistake, " the clinically blind politician said in press conference later in the day.

FORBES: Blair Loses Ally After Company Directorship Fiasco

This is a quintessential misdiagnosis of a problem, and I submit that the same mistake would have been made by a broad cross section of big firm leaders.

FORBES: Law Firms and Overcharging: The System Itself Is Rotten