Near the beginning of the episode, as Weller and his friend are walking together and the camera repeatedly switches viewpoints, Weller is alternately seen with both hands full and with the coffee cup and lunch bag held in a single hand.
This episode appears to take place shortly after the previous one - but Weller's neck is fully healed without even a scar.
at the 5:36 Weller is walking with Allie, he has a coffee and a bag on one his hand and the other hand is free behind his back, when he cross the door the coffee is on the free hand.
Sarin does not "liquefy organs", although the primary cause of death is correctly described as asphyxia owing to the loss of control over the muscles involved in breathing.
Near the beginning of the episode, Allie brings Kurt his "favorite", a poppy seed muffin. Poppy seeds can trigger a false positive urine drug screen for morphine, something which both a U.S. Marshal and an FBI special agent would know because both can be subject to random drug screening. Their characters would not logically do that.