The small, feather-like "spikes" on the Blue Falcon's suit often intersect and visibly clip into each other as he moves.
In the flashback scene, when the gang is chased by the ghost in the haunted house, the ghost appears to be flying by his own as there is no string holding him. But before they realize he's fake, a string suddenly appears.
The opening prologue is set in 2009. Despite this, and the fact that Shaggy is shown to have all the latest tech, his games console in his bedroom is a Super Nintendo, a system that went of mainstream use in the 90s.
While trapped in Dastardly's brig, Daphne says that Scooby or Shaggy would sit in a rigged chair or otherwise reveal a trap door. In most of the TV shows it was Daphne who would accidentally trigger some kind of trap. That was the reason for her 'Danger-prone Daphne' nickname in the original shows.
During the opening scenes, Scooby steals a spit of gyros meat. The officer reports a "grand theft gyro", pronouncing it "jai-roe" and continues to pronounce it that way. Gyros is pronounced "yee-ros" and none of the jokes work as a result.