Mac refers to himself as a Lieutenant at the time of the 1983 Beruit Marine Corps Barraks bombing and there is a photo of a Marine Corps ID showing Mac's rank as "LT" (an officer), but another document shows him separating from the Marine Corps in 1992 with the grade of "Sgt" (an enlisted rank), which would have been a demotion and not at all in line with Mac's character.
When Mac disarms the second bomb, the cell phone is attached to the C4 with tape over the earpiece and the screen clearly visible; When Mac answered the phone, and when Bonasera begins examination of the phone in the following scene, the tape has been moved and the screen is wrapped completely with the earpiece left exposed.
In the season 2 finale (#2.24 "Charge of This Post"), Flack is seriously injured. His left abdomen is split open by debris in a bombing and the right side of his neck is also injured. In the premiere of season 3 (#3.01 "People With Money") he is showing scars on the left side of his neck to two women.
While he is on the operating table, in 2.24, a tattoo is clearly seen on Flack's right bicep when Mac is photographing his injuries. In Season 4 (4.03 "You Only Die Once"), Flack is making out with his girlfriend and his tattoo is gone.
In season 6 (6.08 "Cuckoo's Nest") Flack lifts up his shirt. The scars from his injury in 2.24 have mysteriously disappeared.
Mac cuts the detonator wires with a metal cutter at the same time. This would complete the circuit (via a short-circuit) and detonate the bomb. Wires are cut either one at a time or if both are to be cut at the same time two different cutters are used to prevent a short-circuit.
In the theater, the detectives are the first ones in to search for the suspect. In actual tactical situations, Emergency Service Unit (ESU) members are the ones that clear buildings and detectives enter once the scene has been secured.
Mac's phone rings and the screen says incoming text message. He then answers the phone and has a conversation. Text messages cannot be answered like a regular phone call as they are non-verbal.
In this episode, the CSIs are shown going through evidence, performing makeshift surgery, running investigations/crime scenes/bomb scares, AND disarming bombs. Real life CSIs are much more likely to specialize in one of the above; this approach was very unrealistically Hollywood.
In Mac Taylor's initial flashback to his friend's death in Beirut, the injured Marine is wearing a OG-106 OD Green cotton uniform, but in 1983 the only branches of service who still wore that uniform were US Air force or National Guard Units. The Marine in 1983 Beirut would have been wearing USMC Camo BDUs (as opposed to the well known Woodland Camo that was later adopted by all the branches of services).
Mac's Marine Corps separation document has "separation" misspelled as "seperation" across the top.