Kevin James makes his first appearance on the series as "Kevin" it wouldn't be until season three that he would appear as his "Doug Heffernan" character
The title refers to Captain Nemo a fictional character featured in Jules Verne's novels 'Twenty Thousand Leagues Under the Sea' (1870) and 'The Mysterious Island' (1874). In the first book he travels under the sea in the submarine, the Nautilus, driven by a thirst for vengeance against imperialism and colonialism in the world. In the second book he helps the castaways survive on the island and dies before the story ends.
Kevin asks Debra how's her sister. You never see Debra's sister Jennifer until S4,E6 (about her becoming a nun), then you never hear about or see her again.