The massive wedding cake Lady D stands on during her boss battle may seem a bit out of place, until you realise that's the point - it's a wedding cake. The bride and groom models on top of wedding cakes are represented by Lady D and her groom machine gun respectively.
Of course Cole was able to afford the funding for The Machine's construction. He likely stole the money from Weasleby -assuming that he wasn't obtaining treasure as Weasleby- if he wasn't getting it from you spending money on the game's various upgrades.
The Machine serves as an evil counterpart to your Golden Robo. Both of them are giant robots with a redheaded pilot that derive their energy source from the puzzle realm, have powerful attacks and a heavy metal theme that plays during their appearance.
Lance Banson showing up after Cole is kidnapped by Weasleby after World 4 seems like a humorous moment and also a way to make sure the player can still buy upgrades. However it makes sense considering that Cole is Weasleby and he likely sent Lance there to keep an eye on things while he was gone and to obtain any last minute funding. It also helps that the man is broke after he was revealed to be bald at the end of World 2's boss fight, so it'd be easy for Cole to convince Lance to tend the shop to earn some money.
The final boss theme being a heavy metal song seems to exist for the sake of Rule of Cool, but then you remember that this is a game that wears it's British themes on its sleeve, so its only appropriate that the final boss theme is a genre of rock that originated in the UK.
At the beginning of the game, Henry recognized Weasleby when he came to visit. And later on, you learn that the Weasleby you've been fighting is Cole in a robot suit. Did Cole kill Weasleby and take his place?
Cole may have masqueraded as Weasleby the whole time. Henry remarks "he's always been a strange one" right after Weasleby left.
If Weasleby is a real person and Cole impersonated him, then how will he react when he finds out that his mansion was trashed during the game's final battle?
While the game ends with Cole being turned into an infant after his attempt to use the Golden Hat goes wrong, it can only end two ways: Either the now infant Cole starves to death in Mysteria due to having no means of getting food, or he'll simply revert to normal upon being separated from the Golden Hat; allowing him to escape and construct a new plan. So not exactly the happy ending as one would expect.
