The agents find a gun in a sofa bed. While it is referred to three times in the episode as a SIG, it is in fact a Glock 17L (a long-slide Glock pistol). What makes this odd is that the agents' sidearms are SIG pistols, so you'd think they'd know the difference.
When Abby is examining the fibers with the microscope, the image displayed on the screen is from an electron microscope, not an optical microscope which she is using.
When you look at the strangled Petty Officers ribbons, he has two National Defense Medals and only one Good Conduct Medal. This is an impossibility. The most recent conflicts to recieve a National Defense Medal were the Gulf War from 1990 to 1995 and the Global War on Terrorism from 2001 to the present. For him to have a service star, he would have had to be serving for both, which to put it with the 2005 air date, would have been at least 10 years.
There are two other clues the weapon found is a Glock 17L and not a SIG. When McGee hands Gibbs the application/purchase form for the 'SIG' you can see a large Glock logo on the form. The second one is when Abby is firing the 'SIG' for ballistics testing you can now even more clearly see that it is a Glock 17L and a SIG.
After McGee charges into the witness' room and fires his shots at the suspect, he attempts to do CPR on the victim. He fails to tip her head back far enough and when he attempts to do compressions, has hands are for too low on the abdomen. He essentially does impressions on her stomach.
At 21:23 the reading on the temperature probe is obviously a decal that has been stuck to the face of the probe.