When Capt. Cragen and and Fin, pull up next to Olivia and Elliot while staking out the victim's school, their cars and the street are wet from rain. When Cragen and Fin start the foot pursuit of one suspect and Olivia and Elliot chase the van driven by the other suspect, the ground is dry, the sun is out and there is no sign of rain.
When Detectives Stabler and Tutuola draw their weapons, there are the sounds of hammers being cocked back. However, the pistols they are wielding are Glock semiautomatics. Glocks are striker-fired weapons with an internal firing pin; there is no external hammer to be cocked back. Therefore, the cocking sound, likely added in post-production for dramatic effect, could not possibly have been made by either detective's weapon.