Oxygen masks were deployed when the cabin became depressurised, forcing the Dublin to Croatia flight into an emergency descent.
Some travellers received medical attention following the diversion, with Der Tagesspiegel reporting that 33 people required hospital treatment.
Local police told the newspaper that some passengers were bleeding from their ears, while others complained of headaches, earaches and nausea.
One passenger also mentioned people suffering from “sore ears” upon landing at Frankfurt Hahn Airport, some 60 miles west of the city, on Friday.
Writing on Facebook, he described how the air went cold before the oxygen masks dropped from above, adding that the plane had to “dive 3,000 metres in less than one minute”.
He then praised the pilots for doing an “excellent job”.
Another passenger, Ruth Cosgrove, tweeted: “Been on a lot of flights in my time but never experienced emergency landing with oxygen masks and the works on flight to our holiday destination in Croatia.”
Ryanair played down the incident, describing the hospital admissions as a “precaution”.
But the company acknowledged that there was a shortage of accommodation for passengers who had to wait until Saturday morning for another flight.
“This flight from Dublin to Zadar diverted to Frankfurt Hahn due to an in-flight depressurisation,” said a spokesman.
“In line with standard procedure, the crew deployed oxygen masks and initiated a controlled descent. The aircraft landed normally and customers disembarked, where a small number received medical attention as a precaution.
“Customers were provided with refreshment vouchers and hotel accommodation was authorised, however there was a shortage of available accommodation.”
The firm “sincerely apologised for any inconvenience”.