But there isn't an opening.
4 seconds sound clip from the Labyrinth (1986) movie soundboard.
You can hear this line at 00:21:08 in the Blu-ray version of the movie.
Quote context
[...]
- Well, you ain't looking right. It's full of openings, it's just you ain't seeing them.
- There's one just across there. It's right in front of you.
- Come inside and have a nice cup of tea.
- You try walking through it. You'll see what I mean.
- What?
- That's just wall. There's no way through.
[...]