The cut on Niki's mouth changes between before she hits the 'shape shifter' and afterwards.
When the recap is shown Noah fires the gun at Thompson head and kills him, with one shot. In the previous episode he fires the gun twice to kill him.
When Hiro appears before Sylar at the end of the episode, he has his sword with the handle pointing towards Sylar and the blade pointing behind him. In the shot immediately following that it is now reversed.
After the fight with Sylar when Peter starts to become radioactive, there is a far off shot of Peter glowing and we can see the bright yellow of his glow emphasized on the ground. However, in the next shot we are right next to Peter and there is no glow on the ground at all, only on his hands.
Hiro's father gives him the sword (on min 5:08), but when Hiro appears in Isaac's loft, he appears without the sword (22:30), and then again, he appears in Yamagato Industries with the two swords (30:16).