When the private jet takes off from Charlie Brown Airport, Atlanta (now Fulton County Airport) with only the dog on board (at around 33min into the film), the runway is clearly marked "12L". There is no such runway at that airport (the three runways are 8/26, 14/32 and 9/27). In addition, the use of "L" indicates there is more than one runway with the same bearing, suggesting a larger airport.