Just before the shooting, Michael remarked that the drapes to the bedroom were open. That led a lot of people here, including me, to believe that Fredo opened the drapes to aid the shooters. If so, it puts the lied to Fredo's statement, "I swear to God I didn't know it was gonna be a hit." Why else would they have wanted the drapes to be open?

I believe that Roth was colluding with the Rosatos. Why else would Roth--who lived in Miami and had business interests in Cuba and Nevada--take the Rosatos' side in an obscure beef with Pentangeli over three territories in the Bronx? IMO, Roth's plan was that Pentangeli would be blamed for the Tahoe shooting and the Rosatos would take over the NY operation run by Pentangili that was Michael's muscle-in-reserve. When the Tahoe shooting failed, Roth's backup plan was to lure Michael to Cuba, get the $2 million from him, have him killed in Havana, then have the Rosatos kill Pentangeli so they could take over NY and weaken Michael's successors.