Dunham's hair is a significantly lighter shade of blonde in the middle of the episode, before reverting to the darker shade with reddish lowlights.
The newspaper article from within the Bible, which pertains to Evelyn Hughes' and baby's death, repeats its content. The paragraphs contain text that repeats with very few changes in each column.
When examining the decomposed body of Mrs. Hughes, Walter observes that she had systemic lupus erythematosus (SLE), and goes on to state that she would have been "incapable of producing offspring." Such a statement is not true. Lupus is an autoimmune disease, and while it can cause complications with pregnancy, many women with lupus can, and do, successfully bear children.
The fishing lure (Night of Desirable Objects), is much too big for the rods and reels shown. The lure, if it actually exists, would be for deep sea fishing, possibly sailfish or tuna.
There is no such thing as the Lansdale Sheriff Department. There is the Lansdale Borough Police Department, and the Montgomery County Sheriff Department. However, sheriff departments don't have much involvement in Pennsylvania. It is more likely that they would be dealing with the Pennsylvania State Police.
It is never, ever explained how John Savage's character, a corn-growing farmer, had the high-tech expertise to genetically hybridize his infant son with mole and scorpion DNA. EDIT: It is stated that he was a doctor, and his laboratory is shown.
The newspaper article is dated 9/18/1992 regarding the investigation into the deaths of Eveline Hughes and son. When their remains are being exhumed, the headstone lists Eveline Hughes date of death as 11/4/91 and Baby Boy Hughes as 11/1/1991.
When Junior Agent Amy Jessup is reading a piece of newspaper found in the Bible, it can be seen that some paragraphs are repeated.
The first time we see the construction crew in Pennsylvania, a train passes through in which the first two have CN in white letters on the side. CN stands for Canadian National, a railway that stretches through Canada and down to the Gulf of Mexico, but does not pass anywhere close to Pennsylvania. This may indicate that this scene was not filmed in Pennsylvania.
The construction foreman states he wants to get home 'before kick-off', which denotes a football game, but the corn is still growing and green, which means it is summer, which is not football season.
When Peter is in the car with Agent Jessup, he is not wearing a seatbelt.