I found some crazy fishing rod situations in my MCPE
A. Fishing a chicken:
1. Chicken faints
2. Fishing bob falls even the chicken is flying
3. Clicking Fish gets back the bob
4. Chicken walks back to you

B. Other Mobs:
1. Mob gets hurt
2. Fishing bob falls
3. Click Fish and bob gets back
4. Mob walks to you

Tested on MyPhone 27