Even though it strives for realism, Apollo 13 is riddled with obscure technical errors. I'll start off with one. Oh, and you're a true PAN if you understand this one
Right after Lovell announces that he sees Oxygen venting from the Service Module, there's a brief close-up of the pressure/quantity guages for the cryogenic tanks. Even though the spacecraft is less than 1/4th of the way into the mission, the No.1 Hydrogen tank only reads 60% quantity, the No. 2 65%.
No wonder they were so concerned about loss of power