Sam's injuries are absent during the Impala ride but the cuts and bruises reappear once he is inside Ava's house.
Amount of beer in the glass changes between shots when Sam is talking to Ash at the bar.
When Gordon is talking to Dean about setting up a trap for Sam, he grabs two Mk 2 "Pineapple" type hand grenades from his bag to show Dean.
In the next scene, when Gordon is setting up the trap, the grenade has changed into an M26 fragmentation grenade with a smooth coating instead. When the trap detonates, it has changed back into a Mk 2.
Sam looks at the spend brass casing from the rifle that was shooting at them and says the shooter was using .223 caliber subsonic rounds with a suppressor. He pronounces it "two hundred twenty three", but as the caliber is representing tenths and hundredths of an inch the proper way to say it is "two twenty three" or "two two three" is also commonly used; someone experienced with firearms would not pronounce the caliber the way Sam did. Also it is not possible to tell if someone was using subsonic ammo just by examining a spent casing; what makes a round subsonic is the weight of the bullet, a subsonic round has a bullet that is heavier than most bullets of that caliber. The extra weight makes the bullet too heavy to travel faster than the speed of sound, so in order to tell if it was a subsonic round one would need to see the bullet before it was fired.