The bloodstains on Grandpa's bandages change constantly.
After the RV breaks down, the group apparently spend several hours tinkering with the engine by hand, but it is not until the second day that anybody gets out a tool box.
When the RV first breaks down, four characters stand outside and say the heat would prevent anybody walking for help. All four are wearing jackets or cardigans of some kind and nobody shows any sign of being even slightly warm.