When Amy is walking away from Jake on the bus to the training exercise, Jake has his hands folded in his lap. The camera angle changes and suddenly his left arm is over the back of his seat.
When quizzing Amy about police codes, Teddy asks her what a 10-51 is. She says it's a "roaming gang," and would require the specification of number and direction of travel. In police code, a 10-51 is a call for a tow truck. Jake then asks what a 10-69 is, which Teddy says is "message received. 10-69 means "clear to copy transmission?"
When Teddy is quizzing Amy on police codes, she states that a 10-54L is an ambulance case, severed limb. A 10-54 is a possible fatality. An L suffix would mean a call is a civil matter, which would not be the case with a possible fatality. A 10-54L is a nonsense code, and has nothing to do with a severed limb.
Captain Holt wears his Commendation breast bar above his World Trade Center Breast Bar. When the WTC bar is worn, it is worn above all other medals, but below the American Flag bar.
In the beginning when they are talking about last years training, the paintball guns have fire/sparks shooting out of them. A paintball gun wouldn't spark/fire like that.