The phrase "mistaken that" is a correct and usable phrase in written English.
You can use it when you want to indicate that someone is wrong in their assumptions or beliefs. For example: "Dan thought that the exam was going to be difficult, but he was mistaken that it was as challenging as he was expecting."
Unless I'm mistaken, that sounds just like Spider-Man 3 – a superhero movie legendary in its bloated naffness.
In the Daschle usage quoted above, a refinement was added to make the message "He was mistaken; that said, I forgive him and will take credit for my compassion".
Mr. Harling said the speech allowed Mr. Assad to try to persuade the undecided that he is still a plausible choice, and reflected a belief in the president's circle — perhaps mistaken — that "people will ultimately come back to them, because they offer more of the prospect of a state".
Second, a T-segment can be mistaken, that is, containing significant energy from two different sources.
He aimed to show that this view of the nature of reason is mistaken, that reason is one and the same in all thinking subjects, that it is universal and infinite, and that thinking (Denken) is not an activity performed by the individual, but rather by "the species" acting through the individual.
"For if you think that by killing men you can avoid the rebuker censoring your lives, you are mistaken, that is not a way of escape which is neither possible nor honourable; the easiest and noblest way is not to be crushing others but to be improving yourselves".
P.P.S. –Reader George Grauke wrote to comment: 'You are mistaken that this will never happen again.
Mr. Zhbankov says the federal government was mistaken; that the committee "didn't study the documents carefully".
Mr. Douthat is mistaken that "courses that social conservatives champion produce unimpressive results -- but so do the contraceptive-oriented programs".
