On Getaway, if the lock ball animation has exactly 3 cars in it, and you hit the gear shift 3 times, you enter Secret Mania. But it's not really worth it.
On Theatre of Magic, when it's counting the bonus scoring, hitting a flipper will cut through the crap and jump to the final value.
On No Fear, when it's counting the bonus scoring, hitting both flippers together will cut through the crap and jump to the final value.
on Doctor Who, if you jump into the Tardis to complete the video mode (rather than just running in), you get 1,000,000 x scoring multiplier bonus points.