-Three sound effects
-Three flames shotting upwards toward Zoro while he is flying back.
-two blocked by Zoro crossing swords but the strenght still pushed him back, 1 impact send his third sword flying.
Also imu didnt sinply use some finger to attack, he was simply making a mudra pose.
Its like naruto openning his palm to condense chakra, sasuke using chidori, the Third raikage using Nukite
Its just Omen attacks signature pose.
If the leakers weren't focused o agenda they would have noticed this too.
And since they say Zoro was one shotted, many of us failed to also pay attention to it at first.