Behind-the-scene or behind-the-scenes

[Nonverbis]

Upstream Proficiency by Virginia Evans and Jenny Dooley.

Oxford dictionary gives "behind the scenes" (https://www.oxfordlearnersdictionaries.com/definition/english/scene#scene_idmg_1).

Could you tell me whether this is a case of typo on the second screenshot?

 

[Tarheel]

I think it should be behind the scenes in both cases. Is that what you mean?

 

[Nonverbis]

Is that what you mean?

What I asked if there is a typo here or not.

 

[jutfrank]

Yes, it's a typo. The 's' was dropped. The phrase is always behind the scenes.