It is the second episode to feature only the two main characters.

This is the first episode of the series not to feature West.

This is the first episode of the series not to feature the entire starring cast.

Note: This is the third episode not to feature the death of a female.

This was the last episode to feature the full opening titles.

Also, this is the only episode to feature something seen or mentioned before.

This is the only episode to feature a pop song.

Note: This is the seventh and final episode not to feature the death of a female.

It was also the first episode to feature a murder in a wealthy rural setting.

This is the only episode from all four series to feature no one other than the regular cast.