Stopover in a Quiet Town - S5-E30
Revealing mistake: The actors are supposed to be in a play set for the huge child, but when she reaches down and picks them up it is obvious that it was filmed in an outdoor setting in a town much bigger than what is supposed to be the play set.
Long Live Walter Jameson - S1-E24
Factual error: When Walter is reading the diary of the Civil War soldier at the beginning of the program, he reads an entry from "Tuesday, September 11, 1864." Tuesday, September 11, 1864 was a Sunday.
Continuity mistake: When Cadwallader puts a seal on the Escape Clause paper, he presses so hard that he manages to lift the whole document with seal. You can see that there is absolutely nothing except for a seal mark on the paper, yet when he drops the paper to the floor some typed text appears on it. Also in the same scene, the seal pattern is square in the first shot, but when the paper drops to the floor the seal mark is round.
From Agnes - With Love - S5-E20
Character mistake: Using a Texas Instruments TI-89 Titanium, the seventeenth root of 9,000,355,126,606 is 5.781163783, which means the first prime number greater is seven.
Visible crew/equipment: When Chris escorts Grandma Bayles up the stairs, a blocking mark is plainly visible at the lower right, chalked on the carpet. (00:05:25)