That was a jump scare, if it’s not apparent.
↓ Transcript
Panel 1 [In the escape room] -
Errol: Hmmm, what's this over here?
Panel 2 -
(Panel goes dark.)
Panel 3 -
*BANG*
Offscreen: AAAHHHHHHHHHHH!!!!
Panel 4 -
Errol: Uh oh.
Offscreen: They said no horror!
Errol: Hmmm, what's this over here?
Panel 2 -
(Panel goes dark.)
Panel 3 -
*BANG*
Offscreen: AAAHHHHHHHHHHH!!!!
Panel 4 -
Errol: Uh oh.
Offscreen: They said no horror!