The waitress in Duke's has one red drink on her tray when she goes to the politician's table but a split second later she walks away with a glass containing clear liquid.
Although the vintage film footage of Hawaii, the nightclub scenes (depicting Duke's in 1963), and the Don Ho music selection of E Lei Ka Lei Lei and Tiny Bubbles did a great job of setting the "flavor" of the era, the flashbacks took place in November 1963; however Don Ho's song selections were not written, recorded and released until 1965 and 1966.
7.62 x 51mm is a standard NATO caliber so it is impossible by just knowing the bullet type knowing which weapon was used. Also there are several types of M40 sniper rifles with different calibers.
The song being played at the club in 1963 was Tiny Bubbles. It was not released until 1966.
In the opening scene, as the camera follows the bellhop carrying a woman's luggage into the hotel, you can clearly see the outline of his wallet in his right rear pocket and the slightly larger outline of his smartphone in in his left rear pocket.