mistake (something incorrect that you do, think or say): I think you have made a mistake in your calculation.
error formal (a mistake): There were several errors in the report.
inaccuracy formal (something that is not completely correct): The article contains several inaccuracies.
blunder (a big mistake, especially because being careless or stupid): He made a terrible blunder and then resigned.
slip (a small mistake, especially because being careless or not paying attention): You made a few slips in the translation. It was a slip of the tongue.
gaffe (a stupid or careless mistake made in public): He always make gaffes in his speeches.
Very interesting words