Plot hole: Scar tells the pack he didn't make it to the gorge in time to help Mufasa. However Zazu was with them at at the gorge. He could have easily told Serabi or any of the other lions on the numerous times he spoke with them, exposing Scar.
Suggested correction: Actually, Zazu wouldn't honestly say that Scar was lying; he left Scar at the gorge, but for all he knows, when Scar talks about not getting to the gorge in time, Scar could just mean that he couldn't find a safe path into the gorge to help Mufasa and Simba escape.
So Scar would say he couldn't get to Mufasa in time. Not the gorge.