When Munch throws Howard into the car they are surrounded by other cars. A split second later when he pulls out of the parking lot they have many empty spaces immediately around them.
In the final scenes of the previous episode the second sniper is shown using a Ruger Mini-14, or possibly an M1 carbine with aftermarket accessories which looks very similar. The shell casings found at the scene of the second sniper's first shooting are identified as being .308 Winchester, which neither rifle is chambered for. At the time this episode aired the Mini-14 was available in .222 Remington, .223 Remington, 5.56x45mm NATO and 7.62x39mm. The M1 has only ever been chambered for the .30 Carbine.
The shooter is said to be using .308 Winchester rounds, and the ballistics expert says the shooter's most likely weapon is a M1A carbine, which is chambered for 7.62x51mm NATO, the military version of a .308, the M1A can fire both types. However the gun the shooter is shown using is actually a M1 carbine, they have very similar names, and look similar but use very different rounds. The scene that gives it away the most is when the shooter is shown loading a magazine, the cartridges are clearly not .308's but are .30 Carbine. The difference being the .30 Carbine is a much less powerful round than a .308, the .30 Carbine is shorter (.308 is 51mm long & .30 Carbine is 33mm) with a straight walled cartridge, the .308's cartridge is a bottle-necked cartridge. Both rifles are equally common, in the mid 90's both were frequently used by SWAT units, it doesn't make sense to call it an M1A .308 and then show a M1 .30 Carbine.
Pembelton in a moment of semi-irrational worry gives his Kevlar vest to his wife to help protect her. However the vests he and the other detectives wear are only level II vests, they provide protection from common low to medium velocity pistols like a .380 Auto, 9mm and .40 S&W. While it would be better than nothing, a level II vest would not stop a bullet from a .308, it would only slow it down by a marginal amount, which is something a police officer would know.
Giardello keeps insisting people wear standard issue police Kevlar vests. As far as he knew the sniper was using a 308, which would easily penetrate such vests.