Colombia keeper Faryd Mondragon set the record for oldest player in 2014 in Brazil by playing at 43 years and three days, so El-Hadary beat the record by a significant amount.
The 45-year-old goalkeeper flew to his right to make a spectacular stop in the 39th minute from Fahad Al-Muwallad's spot-kick, awarded for handball, at the Volgograd Arena.
However, he could do nothing about a second penalty awarded to Saudi Arabia and was beaten by Salman Al-Faraj.
That was the 18th penalty sanctioned so far at the finals, equalling the record for a single World Cup with the action only barely past the halfway stage.
Almuwallad had earlier missed a chance to equalize when El Hadary saved his penalty.
Liverpool superstar Mohamed Salah opened scoring for the north African outfit in the 22nd minute with an assist from Abdalla El Said.
Mohamed Salah stylishly broke the deadlock in the match with his second strike of the tournament.
Going into their final Group A encounter the teams knew their World Cup chances were over, having both lost their opening two games.
Saudi Arabia played their best match of the tournament, showing quality football virtually throughout the entire 90 minutes.
Saudi Arabia midfielder Abdullah Otayf completed 110 passes in this match, the most by an Asian player in a World Cup match since 1966.
There had been confusion before the kick off about whether Salah would play when a team sheet showing him not in the starting line-up was posted on an Egypt account on Twitter, only to be replaced minutes later by another that included him.
Always available for the ball, the 28-year-old dictated the game for Pizzi's side with his penetrative passing and accurate crossing.
The Saudis are looking desperate to avoid finishing at the bottom for the fourth time while victory for Cúper's men would be their first after unsuccessful appearances in 1934 and 1990.