Questions & Answers about Если кто-либо заметит ошибку, скажите мне.
Кто-либо means anyone / anybody / whoever it may be.
In this sentence, если кто-либо заметит ошибку means if anyone notices a mistake.
For an English speaker, an important point is that кто-либо is a bit more formal and impersonal than кто-то.
- кто-либо = anyone, often in formal, written, or general statements
- кто-то = someone, often more neutral or conversational
So you could also hear:
- Если кто-то заметит ошибку, скажите мне.
That sounds a little more natural in everyday speech, while кто-либо sounds more formal.