There are several synonyms for the phrase "was incorrect." One way to express this is by using the word "mistaken," which means to be wrong in one's beliefs or actions. Another synonym is "inaccurate," meaning an incorrect or imprecise measurement or information. Additionally, "wrong" is a simple and direct way of expressing that something was incorrect. "False" is another alternative, which implies a deliberate misrepresentation or deception. Finally, "erroneous" means something was incorrect due to an error or mistake. Using any of these synonyms allows for greater variety and precision in expressing the concept of being incorrect.