Sullivan Walker Now
Walker had roles in tons of films and shows after playing that subway guy. Maybe you recall when he played Dr. James Harmon on The Cosby Show from 1988 until 1991. Also he was on shows like The Pretender and Law & Order: Special Victims Unit. His last role was alongside 50 Cent in Get Rich or Die Tryin (2005). Sadly, he died in 2012, only three months after his 65th birthday.
Barry Kivel
Yes, Barry Kivel played the drug user in the film. Clearly, his small role made an impact on the audience. Before this crocodile film, he was in The Natural, a baseball movie about Roy Hobbs. In addition, he played a part in Turk 182! (1985) alongside Robert Urich and Kim Cattrall.