If you chose to save Nick, he reloads his bolt-action rifle with four rounds and fires it in a semi-automatic manner. Bolt-action rifles such as the Winchester Model 70 which Nick uses can only be fired once before inserting a fresh round in the chamber.
About five seconds after Clementine pours peroxide on her arm, her hand goes through the table.
When Nick and Luke are putting Clementine in the shed, Nick's rifle jiggles around in his hands.
When Clementine reaches for the needle in the medicine cabinet, it appears in her fingers at a different angle than if she pulled it out.