The first 4 combinations are possible combinations for the Lab, the next 5 are possible combinations for the Safe.

Password - Result:

7572 - Lab combination
5858 - Lab combination
3301 - Lab combination
8640 - Lab combination
3621 - Safe combination
0120 - Safe combination
1230 - Safe combination
1029 - Safe combination
4186 - Safe combination

Note: This trick only works with Razor. Get the Hamster from Weird Ed's room and put it in the microwave. Close the microwave and turn it on. Take the remains of the Hamster and give it back to Weird Ed. He will be so mad that you killed his hamster that he will kill you.

At any time before Dr. Fred plays the fixed Meteor Mess game (meaning you have repaired the wires in the attic), you can enter 0000 as the inner door combination and the door will open. Presumably, the door combination is not stored in memory until the Dr. Fred Meteor Mess cut scene plays. The Dr. Fred attempting to play Meteor Mess cut scene will not set the inner door code.

Exploiting this glitch will allow you to start the game with Dave and one other kid, instead of Dave and two others. To do it you must click on the kid you want to accompany Dave, and as fast as you can click on 'start'. If you've done it right, the 'start' button will become a garbled mess. Click on it again and the game will start, but you'll only have Dave and whichever kid you clicked on in your team.

When you first go into the kitchen at the beginning, Nurse Edna is waiting there for you, and you have to outrun her or she'll get you. If you go the pause menu (where you can save, reset, etc.) and unpause, or switch to another kid and then back, she'll be gone.