Other mistake: Spider-Man is shown web-slinging past several glass buildings, but he does not cast a reflection in any of them. (00:00:10)
Continuity mistake: When Peter and Debra are approaching Dr. Connors' office, the nameplate on his door misspells his name as "DR. CURT CONNeRS". After they have entered the lab, the nameplate is shown to have the correct spelling. (00:06:10)
Deliberate mistake: When the sewer worker is trying to escape the Lizard, the fast lanes in both directions of traffic are visibly clear for several blocks, which is extremely unlikely in downtown New York. (00:01:10)
Answer: I believe it was just a way to try and show the suit is "oily" or reflective. It also helps define the character's features since otherwise, he'd just be a flat black color. It's similar to how the black suit Spidey had blue outlines. (I don't know why they chose a pink/red color... maybe because red is associated with power/fire/war, so it's a more "evil" color?)
TedStixon