This is a combination of work from Sammy on the original Lost Cave, and my own stuff. Mostly, hers is the stuff concerning the mailing lists and Maria, but anything regarding the site, which I, Sarah, maintain and therefore have to keep updating, is my work.
Pick your poison:
The Lost Boys Mailing List | The FanFic Mailing List | List Mumbo-Jumbo
Kelly Jo Minter is listed in the credits of The Lost Boys as Maria, but many of you have had a difficult time figuring out just where she comes in. Below are some pictures that will tell you exactly where Kelly Jo Minter makes her two appearances as Maria.
Her first appearance is when Lucy ambles into the video store to ask Max if the lost little boy’s mother is inside. As the Lost Boys round the corner, Paul says,

On the right side of the screen, you’ll be able to spot Maria.
Her next appearance is when Lucy calls Michael from the video store to ask if he’ll stay home with Sam that night because she has a date with Max.

Behind Lucy, you can see Maria smiling teasingly at Lucy.
And there you have it. Mystery solved! I believe she must have had some speaking parts in the movie that they cut out for time, because Maria does speak in the novel. If you can find the Lost Boys novel, you’ll be able to read Maria’s “dialogue.” Keep an eye on online auctions such as eBay and Yahoo! The novel shows up there surprisingly often, for an out-of-print book.
I hope this was of service to you. Thanks for visiting the Lost Cave!