When Spencer is talking to Rich while the group loads the truck, Glen is seen walking into the garage as Spencer says "Take care, Dad." However, when the camera pans right to reveal Maggie leaning against the wall and Tara exiting the garage, Glen enters again, despite not having left.
Fragmentation grenades have a kill radius of 5 meters (~15 feet) and a casualty radius of 15 meters (~45 feet). It's impossible that the only effect Glenn and the group experienced was concussion. They would have been severely wounded or killed by the fragmentation and the cardboard boxes and packing peanuts would have done virtually nothing to impede the shrapnel.
A grenade would not be set off by being hit by a bullet. Even if the bullet penetrated the grenade's casing, which the 9 mm Aidan is using would not do, it still would not set it off. Neither the bullet's copper jacket or its lead tip make sparks, so there would be nothing to ignite the gun powder in the grenade. The only possible way to set off a grenade by shooting it would be for the bullet to somehow knock the grenade's pin out, which would be extremely unlikely in any case, but the grenade detonated as soon as it was hit by the bullet, if the bullet had knocked the pin out there would of been about a 5 second delay before it detonated.
The song that plays when the crew gets in the van to scout is "Internet friends" by Knife Party, released in 2011, a year later than the start of the series.
A copy of Shaquille O'Neal's autobiography, "Shaq Uncut" can be seen in a pile of books in Deanna's home. The book was published in late 2011, which is a year after the outbreak was presumed to have taken place.
Daryl leaves on a 4 cylinder (probably Japanese) motorcycle, but, the sound effect is of a 2 cylinder (probably Harley-Davidson) motorcycle.
Daryl builds a new motorcycle, still oblivious to the fact that something that loud would draw the attention of both walkers and the living who would normally be a safe distance away. It never occurred to him that his other motorcycle would have been drawing many of the walkers to the prison at that time.
Glenn is given leadership due to his "experience" in scavenging, but he shows utter incompetence at every step: He doesn't make sure his group has multiple possible escape routes. He doesn't eliminate threats (even noise). He forgets to bring enough ammunition for a typical walker encounter. He doesn't even think to use poking and slashing tools against walkers grabbing at them. Etc.
Abraham's security setup is bad, both in terms of walker and human threat. This, coupled with his lack of understanding the experience of his crew with guns and dealing with walkers, unintentionally casts doubt that he was ever in the military (much less a sergeant).