YOU SAID:

last night I saw my friend eat ice cream

INTO JAPANESE

昨夜、友達がアイスクリームを食べるのを見ました

BACK INTO ENGLISH

I saw a friend eating ice cream last night

INTO JAPANESE

昨夜友達がアイスクリームを食べているのを見た

BACK INTO ENGLISH

I saw my friend eating ice cream last night

INTO JAPANESE

昨夜友達がアイスクリームを食べているのを見ました

BACK INTO ENGLISH

I saw my friend eating ice cream last night