There is zero evidence suggesting the Fredo knew about the hit.
It's a murky situation all the way around - what Fredo was told, what he was offered, what he finally did. I tend to think now that Coppola and Puzo reached a place in the script where they realized that explaining the hit would result in the audience cheering when Fredo got his, so they just went silent about it.
Spot on! Very murky indeed
My take too, Coppola and Puzo were mystified, clueless themselves at explaining so just left things hanging but we are not going silent about it! We'll get there! Pete -- we'll get there --
Coppola and Puzo did us a huge favour! that we are still debating....
- What did Fredo think was going to happen?
Fredo told Michael, "He [Johnny Ola] said there'd be something in it for me." He betrayed his brother for personal gain. "I swear to God I didn't know it was gonna be a hit." In other words, Ola didn't tell him it was gonna be a hit, and Fredo didn't ask why Ola wanted him to open the drapes to Michael and Kay's bedrooom. What did Fredo think was going to happen?
