No one really looked at this event when it happened so the cover story was accepted as gospel.
Some obvious problems with the official story:
If this was an attack on the US, then why were the vast majority of the victims Kenyans?
Where were the US Marines who guard embassies all over the world? The guards at this embassy were said to be unarmed. Really?
The US ambassador to Kenya vehemently requested greater security before the attack. Her requests were ignored.
Why did the FBI keep its top Osama bin Laden, John O'Neil, away from the investigation?
How did a truck bomb cause a modern office building to collapse completely? Physics doesn't work that way.
A grenade thrown into the truck by a fleeing terrorist detonated the truck bomb? Really? And he was able to run fast enough to get away even though the blast wave was apparently strong enough to turn concrete into dust at a distance? (an impossibility by the way.)
Takeaway: The same guy who "investigated" the Oklahoma City bombing was sent in to cook up the story about this one too.