Comment by aaronmdjones

Engine overheating even on idle thrust (if this happens after V1, you would idle it and continue the takeoff anyway; you are beyond the point at which you can safely abort).

Engine oil leak has drained the oil completely and the engine is about to fail catastrophically (unlikely on takeoff but you never know).

Engine is on fire (out of all of the things that can go wrong with an engine during takeoff, this is very likely).

Engine has blown up (ditto).

Engine is missing from the aircraft (not likely, but engines have fallen from planes on takeoff before).

Debris / Ash / etc is in the engine (not likely).

Severe fuel leak (not something I'd worry about during takeoff).

Probably other reasons I can't think of.