[scooter] said:
Are there any big plot holes in this movie? ... Sonny's death doesn't quite make sense - in the way it was set up and then how Carlo wasn't immediately killed - but its really not a plot hole as much as something that's just a little far fetched.
Sonny's death is a plot hole
Carlo beats Connie, which sets into motion the complex Sonny assassination plan.
The plan was after the beating, to have multiple gunmen waiting and ready to kill Sonny at the freeway. Having multiple gunmen with cars blocking means they would have to KNOW he'd be there.
The complex assassination plan begins with some girl phoning asking for Carlo with Connie answering. Carlo enters and THE PLAN was that they would know that she'd go off on Carlo who would beat Connie severely to the point that Connie would instantly phone Sonny. Timing was be crucial since they had multiple gunmen and cars ready to block Sonny at the freeway.
In a later scene we see the last thing Connie would want was for Sonny to beat or kill Carlo so she would not immediately call Sonny.
The next part of the PLAN was that Sonny would go ballistic and leave a well guarded compound, in the middle of a mob war, without any protection as soon as he got the call. Tom Hagen told guys to go with Sonny so the plan was all based on Connie immediately phoning Sonny, Sonny losing his mind and ditching all protection, and for the assassins to kill Sonny before any protection got there.
If Carlo was against the family and had THAT MUCH information on the inner workings of the Corleone family he'd figure out a better plan and he'd realize they would figure out his betrayal and they would kill him.
It is the weakest plot point in an excellent movie. I cringe at the logic but the killing of Sonny is a vivid scene so most tend to overlook how the weakest plot point set up that scene.