Miscellaneous
A glitch/oversight in the game causes the player to keep weapons collected in a level even if the level is aborted. Money accumulated during the level is removed as it should. This means that a player can start a mission, pick up a weapon power-up, abort the mission and sell the weapon. This allows the player to gain money without having to finish any levels. It is possible to use this method to repeatedly accumulate phase shields beyond the purchase limit of five.
If the game is started when the computer's internal clock matches one of several predetermined dates (for instance, December 25, one of the programmers' birthdays, etc.) additional objects or enemies will appear on each stage which take the form of cows, monkeys, lizards, etc. This also changes the opening title screen and sound effects.
One can also activate these additional enemies by pressing all the buttons that appear at the bottom of the loading screen (to do this using the keyboard, not the mouse, press the 'S' key, then the '1', '2', and '3' keys at the episode selection screen).
Read more about this topic: Raptor: Call Of The Shadows