Corrected entry: Towards the beginning of the movie when John drops off his wife, the scene pans upward revealing a sign saying "Santa Barbara Airlines". That airline does not leave from South Florida, where they are suppose to be.
Corrected entry: When John is parking his car, you can see a set light at the back glass window.
Correction: During which scene? And in which car? He drives a lot, and in different vehicles in the movie.
Corrected entry: In the scene where John and Jenny have moved to their new home in Boca, there is a scene in the driveway where John is in front of a new Volvo. He is then seen driving his old Honda Accord when sitting in the driveway looking at Jenny. He later is seen with the new Volvo again.
Correction: This submission assumes that John got rid of his Honda immediately after buying the Volvo, when to me John was simply reluctant to let Marley sit in his brand new Volvo as he has a habit of ripping things up. The next time you see the Volvo is significantly further in the timeline of the movie and it's no longer brand new.
Corrected entry: When at the airport, a Toyota Tercel is being driven. In the next scene, it is clear they are in a Honda. A different car, different color and different body style. Toyota Tercel was a red hatchback. Honda was a blue sedan.
Correction: It is an accepted movie convention to not show every single detail of what John Grogan did, after he dropped his wife off at the airport. As you said, it in the next 'scene', which would be a scene that would be further on in time to the previous scene. Absolutely not a mistake.
Corrected entry: When John takes Jenny to the airport he is driving one car, but is in a different car when he arrives back home.
Correction: This has already been corrected. The shot of John in the Toyota and then the following shot of him and Marley in the Honda is not meant to be taken as happening immediately after, some time has passed between the scenes. Not a mistake.
Correction: This is no mistake, Santa Barbara Airlines flights out of Miami, you can check it by yourself at www.sbairlines.com and YES, that's in fact the Miami International Airport, I can confirmed it as I'm from Miami.