Is this sentence correct?
Yesterday, you made very few grammar mistakes while talking, almost any.

Question

Answer

Not really. 
I believe you meant "Yesterday, you made very few grammar mistakes while talking, if any."
or "Yesterday, you made very few grammar mistakes while talking, almost none."
Hope this helps!

Answer

Yesterday, you made very few grammar mistakes while talking, HARDLY any.
Yesterday, you made very few grammar mistakes while talking, almost NONE.

Both of these essentially translate as "casi ningún error" in this case.

Answer

Almost correct! Just change one word.
I think you mean to say:
Yesterday, you made very few grammar mistakes while talking, almost none.

Answer

Accidentally posted here instead  of in the answers. Moving my comment....

Nie przegap okazji, by nauczyć się języka w zaciszu własnego domu. Przejrzyj naszą ofertę doświadczonych korepetytorów i zapisz się na pierwszą lekcję już teraz!