Substitute Matej Šakota nearly made a dramatic introduction for the hosts, twisting and turning in the area before getting a low drive on target, only for Henderson to react smartly at his near post.
But in the aftermath, as Henderson moved to regain control of the ball, it touched off the arm of Muñoz. Originally not spotted by the official, a VAR review asked the referee to check, but no penalty was awarded.
There weren’t many chances in the final ten minutes, as both teams looked reasonably satisfied with the draw. Pino’s free-kick was nearly flicked in by Sarr at the near post, but Karacic was alert.
In the end Palace had to settle for a 1-1 draw, leaving the tie evenly poised ahead of the rematch in South London.
The Eagles return to action on Sunday when Wolves visit Selhurst Park in the Premier League (14:00 GMT), with the return leg of this tie taking place next Thursday (20:00 GMT).
**Palace:** Henderson (GK), Richards, Lacroix (Canvot, 64), Riad (Mitchell, 87), Muñoz, Wharton, Kamada, Sosa, Sarr, Strand Larsen (Guessand, 87), Johnson (Pino, 64).
**Subs:** Benítez (GK), Matthews (GK), Clyne, Cardines, Hughes, Rodney, Devenny.
**Zrinjski Mostar:** Karacic (GK), Vranjkovic, Barisic, Dujmovic, Mamic; Djurasek, Savic, Abramovic (Memija, 76), Ivancic (Lagumdzija, 89), Mikic (Sakota, 76), Cuze (Juric, 95)
**Subs:** Bogdan (GK), Sajko (GK), Karacic, Arapovic, Nalic, Surdanovic, Cavar, Majic