After trying to push Dawson's car under the train and shooting him, both his brothers get out of their trailer, only to find out an empty car. Dawson managed to slide out and hide under it, yet none of his brothers saw him get out and hide.
When Dupree telephones Amanda for the first time, he asks for Amanda Collier. Tuck knew that Amanda was married, and thus her name is Amanda Reynolds. The use of her maiden name is arguably only to provide the context to the viewer of Amanda having been Amanda Collier in high school in the 1992/93 scenes.