Level skip:
Hold A + X + B + Y to advance to the next level.

Level Password
2 TLPT
3 GRND
4 LLMO
5 FLOT
6 TRSS
7 PRKS
8 CVRN
9 BBLS
10 TR33
11 VLCN
12 QCKS
13 PHR0
14 CIR0
15 SPKS
16 JMNN
17 SNDS
18 TMPL
19 TTRS
20 JLLY
21 PLNG
22 BTRY
23 JNKR
24 RVTS
25 CBLT
26 HOPP
27 SMRT
28 V8TR
29 NFL8
30 WK99
31 CMB0
32 8BLL
33 TRDR
34 FNTM
35 WRLR
36 PDDY
37 TRPD
38 TFFF
39 FRGT
40 4RN4
41 MSTR

Two Blue keys:
When facing the final boss, Tomator use Baleog when you get to Section 2 (Using Baleog to get past Tomator). Shoot Tomator as he is falling down to Section 3 (using Erik to get Tomator). When you get the "Blue Key", two of them will appear in your inventory. Note: Section 1 is when you use Olaf. Section 2 is when you use Baleog. Section 3 is when you use Erik. Section 4 is when you use all the Vikings.