После спектакля мы ещё раз открыли программку и прочитали, кто играл главные роли.

Because после normally requires the genitive case.

• Dictionary form: спектакль
• Genitive singular: спектакля

So:

• после спектакля = after the performance

This is a very common pattern:

• после урока = after the lesson
• после фильма = after the film
• после работы = after work

Ещё раз means again, once more, or one more time.

Literally:

• ещё = still / more / yet
• раз = time / occasion

Together, ещё раз is a fixed expression meaning:

• мы ещё раз открыли программку = we opened the program again / one more time

So you should usually learn ещё раз as a phrase.

The basic form is программка.

In this sentence, it appears as программку because it is the direct object of открыли and is therefore in the accusative singular.

• Nominative: программка
• Accusative: программку

So:

• открыли программку = opened the program/booklet

In a theater context, программка means the program, playbill, or small booklet with information about the performance and cast.

Программка is a diminutive form of программа.

That often suggests something:

• small
• informal
• familiar
• physical, like a little booklet

In theater Russian, программка is very natural for the small printed program you get at a performance.

So while программа is the general word for program, программка often sounds more like the actual little paper booklet in your hands.

Both verbs are:

• past tense
• plural
• agreeing with мы = we

The ending -ли marks plural past tense:

• мы открыли = we opened
• мы прочитали = we read

Compare:

• я открыл / открыла = I opened
• он открыл = he opened
• она открыла = she opened
• мы открыли = we opened

So the form is chosen because the subject is мы.

They are perfective because the sentence describes completed actions:

• they opened the program
• they read the information

Perfective verbs often answer the question what happened / what did they do?

Here:

• открыли = opened
• прочитали = read through / finished reading

If imperfective were used instead, it would sound more like process or repeated action, not a single completed event in the story.

So this sentence moves the narration forward with completed actions.

Because кто играл главные роли is a subordinate clause.

The main clause is:

• мы ещё раз открыли программку и прочитали

And what did they read?

• кто играл главные роли

So the structure is:

• прочитали, кто играл главные роли
• read who played the leading roles

In Russian, subordinate clauses like this are normally separated by a comma.

This is a very common question.

In standard Russian, when the subject is кто, the verb is usually put in the singular.

So:

• кто играл? = who played?
• not normally кто играли?

In the past tense, that singular form is usually masculine singular by default:

• кто играл
• кто пришёл
• кто сказал

This happens even if the answer could be several people.

So in this sentence, кто играл главные роли means who played the leading roles, and the singular verb is grammatically normal.

Because играть роль is the normal expression for to play a role in theater.

Here the sentence is about identifying the cast:

• who was playing the leading roles
• who played the leading roles in that production

The imperfective играл works well because it names the actor-role relationship, not the completion of a one-time action.

Сыграл is possible in some contexts, but it more strongly emphasizes a completed performance or achievement:

• Он сыграл роль Гамлета = He performed / played the role of Hamlet

In this sentence, where they are reading the program to see the cast list, кто играл главные роли is the most natural choice.

It is accusative plural because it is the direct object of играл in the expression играть роли.

Basic form:

• главные роли = leading roles

For inanimate plural nouns, the accusative looks the same as the nominative. So although it looks like nominative, here it functions as accusative.

Compare:

• Nominative plural: главные роли
• Accusative plural: главные роли

That is why the form does not change.

Yes. Very literally:

• играть = to play, to act
• главные = main / principal / leading
• роли = roles

So:

• играть главные роли = to play the leading roles

In natural English, we usually say:

• play the leading roles
• star in the main roles
• play the principal parts

Yes. In Russian, читать / прочитать can introduce the content of what was read.

So this structure is normal:

• прочитали, кто играл главные роли
• read who played the leading roles

The idea is that they looked in the program and read the cast information.

English often does the same:

• We read who played the leading roles.
• We read who was in the cast.

So this is a straightforward and natural construction.

Russian word order is flexible, and placing После спектакля first sets the time frame immediately:

• После спектакля = after the performance

This gives the listener the scene first, then the action:

• After the performance, we opened the program again...

That is very natural Russian narrative style.

You could move the phrase, but the emphasis would shift slightly. Starting with it makes the timing feel like the backdrop for the whole sentence.

Yes, Russian word order is fairly flexible.

For example, you could also say:

• Мы после спектакля ещё раз открыли программку и прочитали, кто играл главные роли.

This still means the same thing.

But the original order sounds very natural because it presents:

1. the time/context
2. the actions
3. the information they found out

So the original sentence has a smooth storytelling flow.