The masks become available to passengers when cabin pressure changed, which was most likely a result of the air rushing outside the plane when the window shattered.
But former flight attendant and US TV show host, Bobby Laurie, reposted the photo to Twitter with a reminder to cover your nose and mouth with the oxygen mask during an emergency.
"PEOPLE: Listen to your flight attendants! ALMOST EVERYONE in this photo from @SouthwestAir#SWA1380 today is wearing their mask WRONG. Put down the phone, stop with the selfies.. and LISTEN. **Cover your NOSE & MOUTH," he wrote.
Source: Twitter: @mtranchin
The post prompted a debate on social media over whether panic had taken over and the passengers had forgotten the flight attendant's instructions prior to taking off.
Masks are commonly used during plane emergencies when there is less oxygen in the cabin, due to the lower levels of oxygen in the air above 10,000 to 15,000 feet.
Without oxygen, the human body is susceptible to hypoxia, a condition which can cause unconsciousness within minutes.
The symptoms of hypoxia include headaches, dizziness, tunnel vision and nausea.
The airline has not issued a statement on whether anyone suffered from hypoxia.
Seven people were treated for minor injuries following the emergency landing, while one woman died as she was nearly sucked out of the broken window.