Don't you know what really happened here? Jackie crawled back onto the trunk of the car to grab the piece of JFK's skull so that some sick SOB couldn't get it.
Now take a look at the actual film.. Moving slowly down a city street in an open limo lined with buildings with open windows and people everywhere. Good god man. you're just asking for it. After the assassinations of Lincoln, Garfield and McKinley you would think that somebody would have seen the vulnerable position Kennedy was being exposed to.
As for the assassination of Oswald as the story goes Oswald was to be transported in an armored vehicle that would back up the hallway almost right to Oswald's cell. Neither the public nor the media would even see him being loaded onto the vehicle. As it turned out the roof was too low to back up the hallway which meant that Oswald would have to be walked out the hallway to the truck. In the confusion of having to get the truck pulled back out and repositioned nobody saw Ruby slip in behind them with a bunch of other people who should not have been allowed in and got close enough to kill Oswald.
Those entire 3 days will go down as one of the worst security breakdowns in the history of the nation.