Here are the mistakes in each sentence along with the corrections:

1. **Mistake:** "much homeworks"
**Correction:** "Our teacher gives us **many** homework today."

2. **Mistake:** "an orange small bag"
**Correction:** "His sister often goes to school with a **small orange** bag."

3. **Mistake:** "doesn't work so hardly"
**Correction:** "John doesn't work as hard as Peter, but he is much more careful than Peter."

4. **Mistake:** "does it cost"
**Correction:** "Do you know how much it costs to fly to Australia?"

5. **Mistake:** "any vegetables"
**Correction:** "She'd like a dozen eggs and **some** vegetables."