The movie was definitely entertaining but there are a few parts to it that made no sense. When he switches from an old car to a brand new one, he is clearly calling attention to himself, not great advice for a drug mule. Also, if he knows that they are looking out for black pickup trucks why doesn't he switch cars or at least get some new paint for the car. Even if the mule himself doesn't have the brains to do that, you would think that the pros would point him in the right direction. These sort of things are common sense and it is hard to take the firm seriously as a result.
Also, at some point it isn't even clear what he is earning the money for, some 100th birthday bash?