How do I get into the castle?

Hint 1 of 5:

The front entrance is difficult.

Hint 2 of 5:

That gate keeps crashing on you!

Hint 3 of 5:

Well, either run through or tiptoe through.

Hint 4 of 5:

Or take the back entrance.

Hint 5 of 5:

You didn't know about the back entrance?