After experiencing a wormhole, Data appears to be lying to cover up the reason for the crew's resulting unconsciousness.

Whoopi Goldberg (Guinan)
Colm Meaney (Lt. Miles O'Brien)
Pamela Winslow (Ensign McKnight)
Rhonda Aldrich (Madeline)
Patti Yasutake (Nurse [Alyssa Ogawa])
Thomas Knickerbocker (Gunman)

• Guinan joins Picard on the holodeck in a Dixon Hill story.
  
• The nurse introduced in "Future Imperfect" is given a first name in this episode, Alyssa. (Alyssa gets a last name in "Identity Crisis".)
  
• This is the first episode where we see Worf teaching his Klingon T'ai Chi class.
  
• The Paxans are an isolationist species. When ships enter their space, they stun the crew and make it appear to be the effect of a wormhole. However, their stun did not work on Data.