We Are Altogether Crazy (1959)

After a gruesome meeting with the tax authorities Alex Alexander takes a drive in the countryside to calm down. While driving, he accidentally runs into an elephant from a circus. When he is stopped by the police and tells them about the elephant they think he is crazy. He is committed to an asylum by the very authorities his taxes are funding. The doctor tries to convince him that the elephants were not really there, but he gets more help from manic fellow patient Knudsen who makes him realize that everybody in the world is crazy in some way.