The production team began by using connections to racing figures Dan Gurney, Phil Hill, and Carroll Shelby, who all assisted them in trying to break through an otherwise reluctant European establishment. The filming process meant disrupting vital practice runs and otherwise getting in the way of the actual racers' activities. The "Grand Prix" team initially faced a particularly lukewarm response from the Ferrari company, with the firm concerned that the movie would overly sensationalize their work. Frankenheimer cut together approximately thirty minutes of detailed footage after filming in Monte Carlo, temporarily halted the movie's production, and sent the short piece over to the company's management. He received such a positive response that he gained unprecedented access, being allowed to shoot inside Ferrari's production floor alongside the real racing vehicles. The director used this budding relationship to push other entities to help with the film-making process. Many real-life drivers of the era ended up making cameo appearances in "Grand Prix", several even briefly speaking alongside the actors.