When Michael arrived at the hospital only to find his father unprotected; wouldn't the guards who were alreay there report to the Corleone Family immediately so they would do something aout it ?

I would kill those guards for leaving the hospital and not reporting. Thats just sloppy work

The guards had been arrested by McCluskey.

True. However, the film, unlike the novel, simply has the police making them leave because "your father had too many visitors."
Even McCluskey stating that he thought he had rounded up "all you guinea hoods" is ambiguous.

I had never given this a second thought, Trilogy. If I were McCluskey, I would have had them arrested and detained (even if temporarily) to prevent Long Beach from being alerted.

Of course, Detective Phillips knew all about this. Why didn't he alert Sonny?

The nurse said that the police made them leave ten minutes ago. It's possible that Phillips didn't have an opportunity considering how quickly they re-arrive (yes I invented a word) to rough around Michael.

In a age without cell phones i dont see how the police showed up so quickly after the gangstes drove by and saw Michael. Its not like they could be waiting around the corner for a phone call, unless they were ready to respond to the dispatch from the impending death of Don Vito, in which case they would be close by.

That's possible. I just thought that from his position as a detective (and a corrupt one at that) that he would know about the deployment of any police forces out of his precinct.

By the way, how was it that Sonny arranged to hire a detective agency and arrange for a phalanx of detectives to arrive so quickly after Michael's phone call to him?

I suspect the detective agency was on some sort of retainer, but your question as to how he had them in place so quickly is a valid one. I'll just chalk it up to dramatic license.

That was exactly what I presumed the plan was. I figure it would have gone something like this:

* Sollozzo and crew roll by the hospital, see that McCluskey has done his job and rounded up all of Corleone's men.

* Sollozzo and crew enter, kill the defenseless Vito

* Leave hospital, rendezvous with McCluskey and patrol to let them know Vito is dead.

* McCluskey and patrol come to the hospital on a beat, find dead Vito, file report.

Instead, they saw Michael and Enzo, so Sollozzo immediately went to McCluskey's hiding spot and was like "I thought you got all of Corleone's men? There were two guys outside" so McCluskey got pissed off because it meant he would have to give Sollozzo back his bribe money (part of why he got so hot at Michael)

Yep id hate to give my grandson's education fund as well. Thanks for tue post, glad to know im not always on my own on here.

The guards were probably Corleone members, not paid detectives. No doubt all or most of them were carrying guns--illegally. That'd be a tailor-made reason to have them arrested en mass and held in jail, and to delay their mandatory phone call long enough for an assassination team to get to the hospital. The replacement guards were probably from a detective agency ("These men are licensed to carry firearms," as Hagenn told Mac).

As the novel states, "It didn't help that some of them were carrying guns."

Vito's intended hospital assassins apparently removed someone(s) from the breakroom in a hurry, but they left the nurse upstairs. I wonder what they were planning for the nurse since she was roaming the floor.

They would have just pushed past her, fired quickly, and left--just as Vito's would-be assassins did, and as Michael did later in the restaurant.