When Palmer examines the X-Ray, the gold heart on Sophie Ranier's eye is red. X-rays films are monochromatic.
The ink of the supposedly tattooed infinity marks on the Ranier's ring fingers have run into the lines in their skin. This is what happens when you use a felt tip or a ball pen. Tattooed ink on the other hand as applied under the skin.
Thermal image cameras don't work through glass.
For the laser bug to work, the windows would need to be closed, so the surveillance thermal imager wouldn't be able to see into the room.
Sophie Ranier's character is supposed to be dead on Ducky's table but her eyelids are clearly fluttering as they open the body bag.
Dr. Mallard is seen about to leave for the USMC Birthday party with the Director. There is a short shot of his display of medals. Although the shot is very brief, it appears that he wears a couple of British campaign 'Stars' - issued only for the Second World War, making 'Ducky' a minimum of 80 years old.
The terrorist disguised as a waiter's lapel microphone's transmitter can be seen clipped on his belt when he leans over to get the key card to open the door to clear the room.
Jenny makes a comment to Gibbs about "the former Czech Republic"; however, the Czech Republic is the current name of the country which, along with the Slovak Republic made up Czechoslovakia.