Here are the corrections for the sentences provided:

1. We must finish harvesting the rice **earlier** this year **than** we **did** last year. (No correction needed, but you may want to ensure consistency in verb tense.)
2. You can find your way around the village **more easily** if you **have** a good map. (No correction needed.)
3. People in the city seem to react **more quickly** to changes than those in the country. (Change "quicker" to "more quickly.")
4. The Sahara is the vast desert that covers parts of eleven countries in northern Africa. (No correction needed.)
5. It took us half an hour **to load** all the goods onto the truck; it was really hard work. (Change "loading" to "to load" and "an hour" to "half an hour.")
6. During our stay in the country last summer, we often played traditional games in the evening. (Change "play" to "played" for past tense consistency.)
7. I don't like rural life, although there are not many good schools or amusement centers. (Add a comma after "life.")
8. People in my hometown are really hospitable; they are always generous and friendly to visitors. (Change "always are" to "are always" for improved flow.)

Here’s the revised version:

1. We must finish harvesting the rice earlier this year than we did last year.
2. You can find your way around the village more easily if you have a good map.
3. People in the city seem to react more quickly to changes than those in the country.
4. The Sahara is the vast desert that covers parts of eleven countries in northern Africa.
5. It took us half an hour to load all the goods onto the truck; it was really hard work.
6. During our stay in the country last summer, we often played traditional games in the evening.
7. I don't like rural life, although there are not many good schools or amusement centers.
8. People in my hometown are really hospitable; they are always generous and friendly to visitors.