When Charlie is sharing a joint with Irene at shuffleboard, the position of their arms and who has current possession of the joint isn't synchronized between shots.
The Witness Security Program , aka Witness Protection Program, is managed by the US Marshalls, not the FBI.
Several characters refer to Melanie as a "monkey". However, she is an orangutan, which is a greater ape, not a monkey.
An arrow sign at the zoo reads "Souveniers"
Compositing error on door handle near the end of the episode: a copy of part of the handle is floating in the air where the handle will end up. Likely the handle was edited to get rid of a reflection, then the start of the shot was extended.