The college card has the key hole ring punched through the side with the magnetic strip. Not only does the hole punch right through the important, information holding, magnetic strip, but if a key ring is on that side with the strip, then you can not slide the card through any magnetic strip reader.
When Horatio reaches down to close a murder victim's eyes, he simply places his hand down over the face without moving it in a downward motion, obviously never touching the man's eyelids. When he lifts his hands, the man's eyelid very briefly twitches, further showing that the actor simply closed his eyes while the hand was covering his face.
We see Eric pushing buttons on a keypad. We hear four clicks, yet he only pushes three buttons. After the four clicks, we see him push the fourth button.
During the flashback of Paul's shooting you can clearly see the dye packs used to make bloody holes appear in his sweater when he is shot.
When Calleigh and Eric speak to Dale Buford he is clearly in possession of a "short barreled shotgun" as defined is section 790.0001(10) of the Florida Statutes, which, in section 790.221 is defined as a felony. Assuming it is not a registered short barreled shotgun or AOW (with tax stamp) under the National Firearms Act, it would also be a federal offense, thus under the jurisdiction of the BATFE (Federal Agents) as well. However, Buford is not detained and the illegal firearm is not confiscated.