Narm: Doctor Doom's voice sounds inappropriately cheesy by today's standards.
Uncanny Valley: "Diablo" has Ben temporarily enter a phase in which he bears a human face, but still has rock-hard skin. The sight of a realistic (by Hanna-Barbera standards) face on Ben's orange and rocky body makes a visually unsettling contrast.
What an Idiot!: Doctor Doom doesn't bother disguising his voice when replacing the photographer at Sue's fashion shoot, but she still doesn't recognize him until after she falls for the trap he planted.