In a Tear Jerker way, Nancy's devotion and love for Sikes (as expressed in her song "As Long As He Needs Me") to the point that she's willing to protect him from jail. Too bad the bastard ends up killing her.
Fagin, lost and broken with nowhere to go, decides to pull a HeelFace Turn and become a new man, until the Artful Dodger emerges from behind a lamppost, offering him a wallet he has filched earlier. Fagin inspects it, before the two sing a reprise of "Reviewing the Situation" accepting their status as criminals and Heterosexual Life-Partners.
Like quite a few child actors of the era, Mark Lester, Oliver's actor in the film, ended up dabbling with drugs as a teenager. However, unlike most of his contemporaries, he managed to turn his life around as a young adult, retiring from his acting career to pursue his education, ultimately becoming a certified osteopath.
The fact that the dog playing Bullseye adored Oliver Reed so much that he had to have his tail taped to his leg in the scenes where he's supposed to be afraid of Sikes, as he couldn't stop wagging his tail whenever he saw him.