Haven’t seen this movie in about forty-two years. And I never noticed this back then, but, I gotta ask: what the heck is a “Srand Prix”?

“No! It says ‘Grand Prix’! Duh!”
It’s presented in Fraktur script, which was incredibly common in Germany until it was verboten by the Nazi party in 1941.
Anyway, that first letter that you may readily and quite erroneously interpret as a G is really an S.
In printed (not hand-script) Fraktur, for reference, here are the letters E-F-G-H-I:

And Q-R-S-T-U:

Context matters, of course. Yes, it’s just a movie. Yes, it’s just a musical. And, yes, it’s just entertainment.
Honestly, people readily understood what was intended.
And that’s what matters.