Factual error: Tim accidentally fires an M2 .50 machine gun while on a tank. Ricochets are shown sparking all over other tanks while people dive for cover. A) Bullets don't spark when they ricochet, and B) the M2 had a blank firing adapter installed; it couldn't have been firing bullets.
Continuity mistake: When Tim stumbles back from the force of the power compactor, he steps in the wet cement behind him. When Al tries to catch his mother's pet turtle before it lands in the wet cement, the spot in the cement where Tim stepped, has refilled itself. (00:15:25)
Character mistake: Before the reveal of Randy's new room in the basement, Tim, Al and Randy are on the stairs. Randy is anxious to see his new "lad pad." When it's time to go in, Tim calls Randy Mark by mistake.
Revealing mistake: When Randy is thrown across the yard by Jason and his friend, you can tell that he is actually just launching himself as you can hear him take four running steps after Brad says "Hey Wilson, how's it going?", followed by Randy appearing onscreen and then jumping off the porch. You can also see Randy's lone shadow running towards the spot where he jumps from while he himself is offscreen. Next you can tell he lands on a crash mat because the leaves on the ground drag behind him as he is sliding across the grass. Lastly, after he says "I'm going to get you for this Brad!", you can see him walking towards the gazebo where Jason and his friend are sitting and just before the shot changes Jason extends his left hand for Randy to give him five.