Thanks, Billy, Gerardo, & Gary! That "speck" has been driving me crazy for the last 45 years and until this morning, it threatened to drive me crazy for the next 45 years. Since the windshield is between the clouds and the camera, there could be no digital remedy.
On every incarnation (theater, television, homevideo) that I have ever seen of HTWWW, I have noticed a black speck in the clouds during Spencer Tracy's opening narration. It would appear to me that it is something that would be easy to correct since it is black against white, and I am surprised...