During the helicopter chase Face throws oil on the other helicopter. In the first shots it's used oil (black), then it's unused oil (brown) and then it's used oil again.
Murdock lands the Bell JetRanger at a gas station to fill up. The JetRanger's Rolls Royce turbine engine runs on Jet-A fuel and would not run properly or for very long and be severely damaged by automotive gasoline.
When the wedding invitation is shown the bride's name is just "Jackie". No one would send out an invitation with just a first name on it.
During the opening sequence view of the city, the filming helicopter's main rotor blades can be seen fluttering at the top of the screen.
The episode purports to take place in Wilson County, Texas, and a sign shows that Wilson County is 60 miles from Dallas. In reality, Wilson County is on the southern border of Bexar County, where San Antonio is, and is around 250 miles south of Dallas. Also, the episodes features mountains, which do not exist in that area of Texas.
In Cutter's offices in the second half of the episode.