Learn Hardcore Russian: Я случайно сделал ошибку и быстро её исправил. - I accidentally made a mistake and quickly corrected it.

Ошибка is a feminine noun in -а. In the accusative singular, these nouns take -у/-ю: ошибк-а → ошибк-у. It’s the direct object of сделал and исправил, so accusative is required.

What exactly does её mean here? Could it mean “her”?

Её is the unstressed object pronoun “her/it (feminine).” Here it clearly means “it,” referring back to the feminine noun ошибка. Without a feminine antecedent, её could indeed mean “her,” but context disambiguates it.

Can I put её somewhere else in the sentence?

Yes. Word order is flexible with slight changes in emphasis:

…и быстро её исправил (neutral; very common).
…и быстро исправил её (also neutral).
…и её быстро исправил (emphasizes that particular thing). All are grammatical.

Why are the verbs perfective (сделал, исправил)?

Perfective past marks single, completed events and moves the narrative forward: you made a mistake and then corrected it. Imperfective would suggest process or repetition:

Я иногда делал ошибки и долго их исправлял (habitual).
Я делал ошибку и пытался её исправлять (ongoing processes).

Could I say Я случайно ошибся instead of сделал ошибку?

Yes. Ошибся (from ошибиться) is a very natural alternative. But then your second clause must change, because ошибся has no direct object:

Я случайно ошибся и быстро это исправил (I quickly fixed it/that).
Я случайно ошибся, но быстро всё исправил. Using её after ошибся would be odd because there’s no feminine object in that version.

Is сделать ошибку the best collocation? What about совершить/допустить ошибку?

All three are correct:

сделать ошибку — neutral, everyday.
совершить ошибку — more formal/literary, sounds weightier.
допустить ошибку — common in formal or technical contexts (reports, rules).

Difference between случайно and по ошибке?

Both can translate “by accident,” but:

случайно = accidentally/by chance (adverb).
по ошибке = by mistake (set phrase), often for choosing the wrong target: по ошибке отправил письмо не туда.
In many contexts they’re interchangeable; случайно is broader.

Why быстро and not скоро?

быстро = quickly (speed of the action).
скоро = soon (time until it happens).
Here you mean you corrected it fast, so быстро is the natural choice. Скоро исправил would mean “corrected it soon (afterwards),” which is a different nuance.

Is the comma before и needed?

No. This is one simple sentence with two homogeneous predicates sharing the same subject (я). Russian does not place a comma before и in this structure: Я … сделал … и … исправил. A comma would be required if there were separate clauses with different subjects.

Can I change the adverb positions, like я сделал ошибку случайно or я исправил её быстро?

Yes, but neutral Russian prefers adverbs before the verb or right after focus words:

Most natural: Я случайно сделал ошибку, …и быстро её исправил.
Я сделал ошибку случайно is possible but can sound like an afterthought or contrastive focus.

Can I drop я?

Russian is not a pro‑drop language. You keep я unless the subject is crystal clear from context or you’re using a very elliptical style (e.g., in notes). As a standalone sentence, keep Я.

Pronunciation and stress tips?

случа́йно (stress on -ча́й-).
сде́лал (the с voices before д: sounds like [зд]).
оши́бку (after ш, written и sounds like [ы]).
бы́стро (unstressed final о reduces).
её (stress on -ё).
исправил́ (stress on -ра-).

Why not исправился?

Исправился is reflexive: “I improved/changed my behavior,” or “I corrected myself (as a person).” To fix a mistake, you use the transitive исправить что: исправил ошибку/её.

Can I say быстро это исправил instead of быстро её исправил?

Yes. Это refers to “this situation/this thing” and is gender‑neutral. It’s a common way to avoid repeating the noun: …и быстро это исправил.

Is ошибка the same as опечатка?

No. Ошибка is any mistake. Опечатка is specifically a typo. If you typed something wrong, you could say: Я случайно сделал опечатку и быстро её исправил.

Could I use а or но instead of и?

Yes, to add contrast:

…но быстро её исправил = “but quickly corrected it” (stronger contrast).
…а быстро её исправил = mild contrast or shift.
И simply sequences the actions without contrast.

Why is её sometimes written as ее?

The letter ё is often printed as е in everyday Russian, so you’ll see ее. Both are acceptable in normal text. Dictionaries and textbooks prefer ё to avoid ambiguity.

Is я always capitalized like English “I”?

No. Russian я is lowercase within a sentence. It’s capitalized here only because it begins the sentence.