After Hansel and Gretel traumatize Garcia with torture and sexual advances, Garcia is left crying about something called Marathon Man. Marathon Man has a well known torture scene in it.
Dutch's past isn't what it seems, which makes him running out of the omake where everyone's de-aged make more sense.
Chaka thinking himself a badass for killing 10 people and asking Revy if she's ever killed anyone makes a lot more sense when one remembers that Japan has incredibly stringent gun control laws. Most criminals don't even have guns. On the other hand, he still thought he could take a woman who killed half his crew (Ginji killed the other half).
The ending theme of the OVA is When Johnny Comes Marching Home, particularly appropriate since Garcia and Fabiola are trying to find Roberta and bring her home. It shifts to being outright brilliant, however, when you realize that the same tune is used for Johnny I Hardly Knew Ye—if anything, even more chillingly appropriate considering what it cost Roberta to get home.
When Rotten the Wizard finaly shows up in the Greenback Jane arc, he makes a long winded speech standing on a rooftop above the protagonist, before being quickly shot by Revy. The position actually forces Revy to aim at his center of mass rather than try a more difficult headshot, or aim for his limbs. Meaning he forced his opponent to shoot him where he is the most protected via his vest.
Lovelace senior was a supporter of the Fifth Republic movement in Venezuela when he was blown up. While being assassinated by some shadowy US forces for supporting a left-wing anti-American movement is an old espionage trope, it's particularly chilling to realize that, had he lived to see the Fifth Republic take power and Hugo Chavez ascend to the presidency, Lovelace would have been among the first of those persecuted by Chavez. After all, he is a patrician landowner, one of the groups that the Chavistas have particularly antagonized.
The assassination might very well be the reason (in the Black Lagoon universe, obviously not Real Life) Chavez came to power by A, antagonizing the populace against the US into supporting Chavez, B, clearing the way for Chavez by removing his superiors.
And all of a sudden, Garcia's future is not looking good...