Visible crew/equipment: When the gang break into the house at the beginning we see Shaggy playing with an old record player. It suddenly turns on with a bang, and if you look quickly when the camera returns to Shaggy, you can see a hand on the left side of the screen (with what looks like the remote to turn the record player on) quickly pull out of view off screen.
Visible crew/equipment: When Fred and Daphne are held by the Tar Monster, you can see a crew member hiding in the background.
Answer: Yes! There was a real Heather Jasper Howe! Like the fake Heather Jasper Howe's True Identity is Jonathan Jacobo! He was arrested with Ned.
No, there is no real Heather Jasper Howe. The movie never shows that.