Chapter 1, Level 4 - How does he use the Axe Twice?
You need to swap the two panels, but then swap them again so he can use the axe twice.
Chapter 2, Level 5 - How do you Avoid the Cop?
When you get on the bike quickly swap the panel with the dog so it follows the bike panel.
Chapter 3, Level 9 - What is the Passcode?
The passcode is the order of the blinking neon numbers which is 4673.
Chapter 3, Level 9 - How do you get the Bonus Photo?
If you reverse the passcode numbers to 3746 you will get the bonus photo.
Chapter 3, Level 11 - What are the Numbers to Unlock the Combination Lock?
The numbers to unlock the combination lock are 6, 12, 6, 18.
Chapter 5, Level 21 - How do you get the Bonus Photo?
You just need to get on the green conveyor belt that is near the end of the level.
Chapter 6, Level 23 - How do you Pass this Level?
Just match the two images against two and one against one. This must be accomplished before the timer runs out.