The ending
As nice as it was for Goldie to come around and go back to Don for the happy movie ending, but I always thought it woulda been more powerful for her to run off with Ralph. Don was wrong, Mom was right, and carefree hippies just don't care about plans or commitment. The end. Sad, but strong ending.
As it played out, it was far-fetched for Goldie to have such a 180 and go back to Don. Especially to sit down and have a sandwich and a beer while her boss/boyfriend is waiting right outside.