Hank tells Peggy that they should buy Bobby a rifle. In reality he already should own a rifle, the 12 gauge shotgun his grandpa Cotton Hill gave him for his birthday in Season 1 episode 7 Shins of the father.
When the clerk takes the rifle out of the display case, she racks the slide, showing that it's a pump action. However, when Bobby and Hank fire it at the gun club, it's firing as a semi-automatic without needing to be pumped.
Hank claims that McDonnell Douglas created the L-1011 jet airliner, when it was actually Lockheed that designed this plane (that's what the L stands for.)
When Bobby is loading the rifle, he's pushing the cartridges into the back of the receiver instead of into the rifle's magazine.
In "How To Fire A Rifle Without Really Trying", he says that when he fires his gun he will imagine a "McDonnell Douglas L-10-11" flying to the target. The L-10-11 was manufactured by the Lockheed Corporation, not McDonnel Douglas.