When Luke and Bo were running away from Boss Hogg's mansion, Luke was wearing a open shirt without white t-shirt under it. You can see his bare chest. When their car was almost hit by a bulldozer, Luke was only wearing a white t-shirt.
This movie is supposed to take place before the 2005 film. In the beginning of the 2005 film, General Lee had no confederate flag, and the 01 was sloppily painted on there. It was made to look like the original later on in the film. In this film, it says it always looked like it originally did.