As is typical in tv/movies, near the end Dr Roshan is about to administer an injection to Zack. Doctors rarely administer medications. They will place orders for a licensed nurse to administer. Then the technique that he attempted to use shows him possibly administering as directly in a vein in Zack's forearm. Also inaccurate. Intravenous medication is done through access such as IV, not directly with a needle. Access to the vein needs to be established before administering medication. Some meds can be caustic to muscle tissue if directly administered without access, or what's known as intramuscular administration (IM). Only appropriate meds should be administered IM and then also only in an appropriate muscle, which the forearm is not.