In the scene where Jack is walking through the water in the sewers you can clearly see that his jeans are soaked up to the knee. In the next scene you can see that his jeans are clearly dry.
When Jack catches up with Cheng on the roof top of the industrial building he tells him to put down his weapon. The breech block of Cheng's gun is pulled back since he is out of ammo. In the next scene Cheng places the gun on the metal bridge with the breech block in its normal position. There is no sound or action that would prove that Cheng released the breech block of his gun.
When Jack is following the Chinese agents and Josh is running with Cheng, we see Josh running upstairs and wearing the identification of "CTU Visitor". Seconds later he's not.
Before Jack and Mike leave CTU to rescue Josh, Mike calls Jack "Josh."