In an earlier part of the level there's exactly the same cluster of crates, containing an ! crate but surrounded by basic crates instead. If the player tries doing the same thing as with the TNTs, spinning the ! crate from its corner, it won't work in the same way. Crash will activate the ! crate but he's also going to hit and smash the left or right wooden crate, respectively. This shows that this glitch is exclusive to TNT crates.