ST:TNG:14 - "Datalore" (Stardate: 41242.4) - this is the 14th episode to go into production but the 13th episode to air on TV. This is a special episode, since it's the one that introduces Data's past - it shows his brother Lore (there will be future episodes with him in it) as well as mention Data's "father" Dr. Noonien Soong (trivia: the name is an homage to Khan Noonien Singh, the villain of Star Trek II: The Wrath of Khan). This episode also introduces Data's off switch, as well as the Crystalline Entity (will be seen again in Silicon Avatar). And, the Chief Engineer Arguile is seen again (this is before Geordi LaForge became the permanent Chief Engineer later on in the series).
