At around 53 minutes in, Chili is on foot chasing someone through a forest. His hands and face are clearly visible several times. And it's clearly shown that he is holding nothing in his hands or mouth. He's running fast, non-stop, and his mouth is wide open. Immediately following one of the cuts, a lit joint has suddenly appears in his mouth.
In the beginning of the movie, Hogan is a janitor and walks in backwards to Bobs office, he takes the tray of pastries from the table and dumps them in his cart but after he tries to tag Bob the tray is back on the table.
At the end of the movie, the group runs out of the hospital room playing tag. Earlier in the room you could see Jeremy Renner's character's wife was standing in the doorway, but in the shot immediately after you don't see her in the hallway.
In the forest scene, Jerry places a boom box on the ground in front of a tree and presses play on the cassette deck. "Crazy Train" by Black Sabbath begins to play and can be heard throughout the forest, but the reels on the cassette never turn while the music is playing.
The goof item below may give away important plot points.
After Hoagie, posing as a janitor and loudly cleaning the room with a large cart of supplies for the first tag is discovered and discussed his plan with Callahan, the cleaning cart has vanished when Callahan goes back into the same office with the reporter.