As Hank speaks as he writes the resignation note, his 3rd line is "with very deep regret". When Peggy looks at it, the 3rd line says "very very deep".
When Hank dials "911" after Mr. Strickland has his infarction he actually dials "900"
Hank explains that tow truck drivers don't need to have a Hazardous Material license to tow the propane trucks. In fact tow truck drivers are required to have all endorsements on their license in order to tow commercial vehicles.
Buck marks off the workday on his Strickland calendar, which is shown in a closeup shot to be Thursday, January 9, 1998. However, this date was actually a Friday; January 9th fell on a Thursday in 1997.