Well if you watch the movie "Music of the Heart", watch when they first buy their puppy. He's a little dark brown/gray dog. Then, later in the movie, which is supposed to be like 5-10 years later, the dog suddenly becomes a golden retriever. They used a completely different dog. They could have at least had a dog of the same color!
The dog in the 10 years later scenes is not a golden retriever! He looks just like the puppy only less grey. As dogs age they lose their puppy fur which can be a different color from their adult fur.