El elenco se sale del personaje entre bastidores.

Because el elenco is a singular collective noun. Grammatically, Spanish treats it as one unit, so the verb goes in the singular:

• El elenco se sale... = The cast breaks character...

This is similar to how English can say the team is or the cast is, depending on style.

If you named the people individually, then you would use the plural:

• Los actores se salen del personaje.

Elenco means cast, especially in theatre, film, or television.

In Spain, reparto is also very common:

• el elenco de la película
• el reparto de la película

Both can mean the cast, although reparto is often the more everyday word in Spanish for a film or TV cast.

Here, se is part of the pronominal verb salirse de.

• salir = to go out, to leave
• salirse de = to come out of, to step out of, to go outside of

So salirse del personaje means something like to step out of character or to break character.

This se is not really reflexive in the simple English sense of himself/herself. It is just part of the way this verb is used in this expression.

Because de + el contracts to del in Spanish.

So:

• de el personaje → del personaje

This contraction is required in normal Spanish.

The only common exception is when El is part of a proper name, such as:

• de El Escorial

But with a normal noun like personaje, you must use del.

That is a very natural question.

In this sentence, del personaje is being used in a generic or collective way, meaning out of character rather than focusing on each individual role separately.

However, depending on context, Spanish speakers might also say:

• El elenco se sale de sus personajes entre bastidores.
• Los actores se salen del personaje entre bastidores.

So the singular in the original sentence is understandable, but a plural version can sound more precise if you want to emphasize that each actor has their own character.

Literally, entre bastidores means between the stage wings / scenery structures.

Idiomatic meaning:

• backstage
• behind the scenes

In this sentence, it means backstage, where the audience cannot see the actors.

It is also used figuratively in other contexts:

• Las decisiones se tomaron entre bastidores.
  = The decisions were made behind the scenes.

Yes, it is a natural and understandable way to express that idea.

Salirse del personaje suggests that the actor stops fully maintaining the role and momentarily becomes themselves again.

Other possible ways to express similar ideas are:

• romper el personaje
• dejar el personaje por un momento
• dejar de interpretar a su personaje

But salirse del personaje works well and sounds idiomatic in an acting context.

Because Spanish often puts adverbial location phrases after the main verb and its complement.

So this order is very natural:

• El elenco se sale del personaje entre bastidores.

But Spanish word order is flexible, and you could move it for emphasis:

• Entre bastidores, el elenco se sale del personaje.

That version puts more focus on where it happens.

Yes. That would slightly change the focus:

• El elenco = the cast as a group
• los actores = the actors as individual people

So:

• El elenco se sale del personaje entre bastidores.
• Los actores se salen del personaje entre bastidores.

Both are possible. The second one feels a bit more direct and personal.

Not always, but it often carries a sense of going beyond a limit, coming out of something, or stepping outside a boundary.

In other contexts:

• salirse del camino = to go off the path
• salirse del tema = to go off topic
• salirse del personaje = to step out of character

So here the idea is that the cast is no longer staying fully inside the role.

Yes, in general it can.

But in this sentence, because of el elenco and del personaje, the most natural reading is the literal theatre meaning: backstage.

If the sentence were about politics, business, or planning, entre bastidores would more likely mean behind the scenes in a figurative sense.