The real Jim Barrett, owner of Chateau Montelena, appears in the film as a vineyard owner who pours a wine sample for Alan Rickman. Mike Grgich, the real-life winemaker at Chateau Montelena (and the man who was most responsible for the award-winning 1973 Montelena Chardonnay), appears in several scenes at the chateau, standing next to Bill Pullman as he takes a wine sample from a barrel.
The Parisian street scenes were filmed in Sonoma, CA using cars provided by members of the Arcane Auto Society car club. The automobile's owners were used as extras in the street scenes that showed their cars.
When they pick up Alan Rickman at his hotel, it is the Toscano Hotel which is in Sonoma, not Napa, CA. You can see part of General Vallejo's adobe barracks next to the hotel. You can also see part of the Sonoma Square behind them.
In-joke: Maurice (Dennis Farina) adds a wry reference to labor issues with film production during Scene 24 (minute 91:54) as guests and judges arrive. He claps his hands and in bad French urges a chauffeur to get moving and park the cars, followed by "Let's go! You're not a Teamster, ya know!"