Fredo's behaviour on New Year's Eve

Question

As many times as I have seen The Godfather, Part II I have never understood a couple of things about Fredo.

At the New Year's Eve party, an hour or so before Michael lets Fredo know that he knows about his betrayal of him to Roth, Fredo slips away, giving a lame excuse that he "needs a real drink". Not long after, Cuban police show up in Roth's room and kill Michael's henchman before he can kill Roth.

I figure this means that Fredo really went to tell Roth's people about Michael's attempt to assassinate Roth. How else would the police coincidentally all of a sudden know that they needed to get to Roth's room? But why would Fredo do this? At the time, he didn't yet know that Michael was gunning for him.

I've never understood this point and I've never seen it discussed anywhere. Your help is appreciated.

The idea that the Cuban police discovered the plot accidentally, as they were merely on their way to Roth's room to rescue him from the ensuing revolution, has merit. But I would point out a couple of things. First, it is never specifically stated in the movie or in any alternative scripts that I have ever heard of. Second, Fredo's behavior at this point still needs explaining. It's pretty clear that he isn't just going to look for a "real drink". Third, as many times as I have seen this scene, I have never detected any surprise on the face of the Cuban commandant. To all appearances, he seems to know exactly what he will find in Roth's room and he is completely ready for it.

If the Cuban police did, indeed, discover all this by accident, if that is the answer to the question, I will show some real temerity and say that this was one of the few missteps Coppola and Puzo made in the script and in the directing of the movie.

Answer 1

At the New Year's Eve party, an hour or so before Michael lets Fredo know that he knows about his betrayal of him to Roth, Fredo slips away, giving a lame excuse that he "needs a real drink". Not long after, Cuban police show up in Roth's room and kill Michael's henchman before he can kill Roth.

There is no indication that Fredo attempts to warn anyone.

Michael tells Fredo that he knows about Roth's machinations and plan to kill Michael when they have a conversation in the square and Michael tells Fredo that..

Hyman Roth will never see the New Year.

So clearly the assassination plot is already underway hours (if not a full day) in advance of the New Year's party and Fredo would have had ample time to warn Johnny Ola or Roth of the plot.

In fact Fredo seems pretty unconcerned about the idea of killing Roth throughout the night out in Havana or at the party on New Year's Eve the next day.

Fredo slipping away with the "needing a drink" excuse happens before Michael reveals that he knows Fredo has betrayed him so this adds no weight to the idea that Fredo attempts to warn Roth.

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If Fredo had given a warning there would have been considerably more security around Roth (and Ola) than what appears to be (initially) a single bodyguard for Roth at the hospital. In fact, during the attempt to kill Roth in his room there are no guards whatsoever...merely a single nurse who is tempted away by other hospital staff to celebrate the New Year.

As for the "police" showing up, you have to recall the backdrop of what is happening in Cuba at the time.

There is an actual revolution going on and the government of the island is fleeing. Roth is a known "friend" to the government and so it's likely that he would be warned.

The screenplay seems to confirm this..

   INT. ROTH'S HOSPITAL ROOM - NIGHT

   Bussetta raises a hospital pillow, and easily begins to
    smother the thin old man, who can barely struggle.

  OUT IN THE HALL

   A detachment of military move quickly, accompanied by some
   of Roth's men, as though they have important news that must
   be dealt with.