I am going to say "The Star Spangled Banner". The line "In the rocket's red glare" has been sung wrong at countless televised events as "And the rocket's red glare". I can think of close to 30 baseball games and a handful of footballs games where the celebrities got it wrong. Then, there are the rest of Americans who sing the wrong song altogether.
For some reason, Americans think it "America the Beautiful" is the national anthem. There are no purple mountains in the national anthem. Does that count as getting the lyrics wrong?