Visible crew/equipment: As Stabler is bringing Saul Picard to the cop car after finding him in the park, a large boom mic is visible in the reflection of the car's window as Stabler opens the door. (00:13:40)
Visible crew/equipment: After Picard headbutts Stabler into the car window and runs away, Benson runs over to comfort him. As she cradles him, the reflection in the side of the car shows the camera person filming as the shot gets closer. (00:14:05)
Deliberate mistake: When James is shot on the courthouse steps, the crowd of reporters that has gathered quickly scatters to escape the gunfire. One of them is a woman in a black windbreaker holding a camera. The camera cuts away briefly and then back to the crowd - you see the exact same people, including the woman in black running in the exact opposite direction as before. The footage was apparently mirrored and repeated for the second shot of the fleeing crowd.
Factual error: The scene where Pierson Bartlett is on the stand, he pulls a spoon out of his jacket. This would never be allowed. He wouldn't get through the metal detector with any metal that could be used as a weapon. He would either have to take it back to his car, or leave it at the security desk.
Answer: I didn't see the show so I don't know the details. A general answer would be because a reckless endangerment charge is easier to prove "beyond a Reasonable Doubt" in court and get a conviction. This charge would not require the prosecutor to prove intent, which would be required for proving aggravated or simple assault. Also, if there were no visible injuries, it is difficult to show bodily injury. Just because the reckless endangerment charge was specifically mentioned, it does not necessarily mean there were not other charges filed. Police often make multiple charges, like lesser-included offenses, so that the defendant's act will fall under one of them if the legal requirements are not met for the others, if they are not sure of the best charge to make (the district attorney knows and can decide), or to have something to plea bargain with.
KeyZOid