Here are the mistakes and their corrections:

1. **Sentence**: "When is your mother's date of birth?"
**Correction**: This sentence is correct as it is. (No change needed)

2. **Sentence**: "In spite of they were tired, they wanted to watch the film."
**Correction**: "In spite of their tiredness" or "In spite of being tired..."

3. **Sentence**: "Did he a doctor or a manager of a computer company?"
**Correction**: "Did he **work as** a doctor or a manager of a computer company?"

4. **Sentence**: "There are less TV programs for teenagers than there are for adults."
**Correction**: "There are **fewer** TV programs for teenagers than there are for adults."

5. **Sentence**: "The distance from Ha Noi to Can Tho is about 1.877 kilometre."
**Correction**: "The distance from Ha Noi to Can Tho is about 1.877 **kilometres**."

These corrections will make the sentences grammatically accurate.