Here are the mistakes and their corrections in the sentences:

1. **When you called me, I am leading a group of visitors at Hoa Lo Prison.**
- **Correction:** "I am leading" should be changed to "I was leading."
- **Corrected:** When you called me, I was leading a group of visitors at Hoa Lo Prison.

2. **She was taking photos outside the Imperial Citadel of Thang Long, I explored the palace and other sites inside the Citadel.**
- **Correction:** Change the comma to a semicolon or make it two sentences.
- **Corrected:** She was taking photos outside the Imperial Citadel of Thang Long; I explored the palace and other sites inside the Citadel.

3. **Mai wishes she lived in Ha Noi so that she can taste many traditional foods.**
- **Correction:** "can" should be changed to "could."
- **Corrected:** Mai wishes she lived in Ha Noi so that she could taste many traditional foods.

4. **Don’t you wish you have more time to pay a visit to the Colosseum?**
- **Correction:** "have" should be changed to "had."
- **Corrected:** Don’t you wish you had more time to pay a visit to the Colosseum?

5. **I wish everybody is aware of the protection of our heritage, so that the future generations can know better about our nation.**
- **Correction:** "is" should be changed to "were."
- **Corrected:** I wish everybody were aware of the protection of our heritage, so that the future generations can know better about our nation.

Make these corrections for proper grammatical structure!