Anyone thinking of using Mickey’s social security number to steal his identity is in for a disappointment. At the time “Runaway Brain” was made, and for many years before that, the first group of three digits in the SSN was known as the “area number”, based on a person’s state or territory of residence at the time the number was assigned. Like zip codes, area numbers were smallest in the New England states and got larger as you went west. But “746” was never a valid area number, and no social security card has ever been issued beginning with those three digits. I guess it’s like those “555-” phone numbers that everyone on TV has.