When Fred applies for the job with Mr. Macyrock, his hair is black. When Fred goes to work that night, Mr. Macyrock's hair is now white.
This episode is set during the Christmas season. Since Christmas is during the season of Winter, Dinosaurs wouldn't be able to survive the cold weather temperatures of Winter due to the fact that all dinosaurs were reptiles, as reptiles are cold blooded animals that are not able to survive cold Winter temperatures.