Here are the corrections for each sentence:

1. My brother used to **go** to the movies with our father.
=> "going" should be corrected to "go."

2. Hoa asked me if I could have a picnic with her in the country **or not**.
=> The phrase "or not" is unnecessary and can be omitted. The corrected sentence: "Hoa asked me if I could have a picnic with her in the country."

3. Most of **the** monkeys both in the forest and in the zoo are **interested** in bananas.
=> "monkeys" should have the article "the" before it, and "interesting" should be corrected to "interested."

4. It takes Nam thirty minutes **to go** to school on foot **every day**.
=> "going" should be corrected to "to go," and "everyday" should be changed to "every day" (two words).

5. Not only Ha but also her friends **were** present at my fifteenth birthday party.
=> "was" should be corrected to "were," and "in" should be changed to "at."