Corrected entry: In almost every scene of Garner in the Yamura, the roll bar does not clear his helmet, a flagrant violation of safety regs. This was because James Garner was so tall that even after removing the seat cushion, forcing him to sit right on the metal body pan, he still didn't sit low enough.
Corrected entry: In the last race of the movie, the Italian Grand Prix at Monza, the cars race on the fully combined 'figure eight' main circuit and oval. The film was made in 1966, supposedly depicting the 1965/66 World Championship season, but the last time the 'figure eight' circuit was actually used for a WC Grand Prix season in real life was in 1961.
Correction: During the overhead shot of Black and Gold GT350 driving around (Disk 2, 46:28), the announcer says "The last time this combined circuit was used was in 1961". I think any movie of this type (Days of Thunder, Le Mans, Little Big League) are not documentaries of a season, they are just using it as a setting.
Correction: In 1966, the year the film is set, the regulations did not require the hoop to be higher than the driver. This is amply proven by looking at contemporary race footage and photos. This weakness in the regulations mostly defeated the purpose of having rollover hoop at all, but that is what was the case.