This page is set up like a near-printable checklist now. You can tick the boxes while you work through the game, but those checks are only local to the page in your browser and do not save if you refresh, close the page, or come back later.
If you just want the short version: the easiest places to miss progress are Back to the Sedgewick and Lair of the Huge Spider. Those are the two five-collectible stages.
Stay Puft collectible checklist by level
Training Day
Open the Training Day walkthrough
Asylum Brawl
Open the Asylum Brawl walkthrough
River of Ooze
Open the River of Ooze walkthrough
NYC Mayhem
No collectibles in this level.
Open the NYC Mayhem walkthrough
Subway Smasher
No collectibles in this level.
Open the Subway Smasher walkthrough
Graveyard Plot
Open the Graveyard Plot walkthrough
Back to the Sedgewick
Open the Back to the Sedgewick walkthrough
Mean Streets
No collectibles in this level.
Open the Mean Streets walkthrough
Lair of the Huge Spider
Open the Lair of the Huge Spider walkthrough
Gates of the Dead
Open the Gates of the Dead walkthrough
Parkview Retribution
No collectibles in this level.
Open the Parkview Retribution walkthrough
Temple of the Destroyer
No collectibles in this level.