D. N. F.
Frannie and I each did this puzzle separately, and we each had the same mistake - IsIS for IBIS (16A: Object of ancient Egyptian veneration). 10D: Japanese P.M. Shinzo (ABE) was no help. Tough luck.
Didn't love TEHEE (33D: Titter), and we've never heard of 18A: "Maria _____," 1941 #1 hit (ELENA), but that's about it. The theme was enjoyable, and there was some quality non-fill. DIPHTHONG (9D: "Oy" or "ow") is lovely, IMPIETY (43D: Ungodly display) is solid, and THERMOS (5D: Lunchbox accessory) takes me back, and even though we never had the game, everyone loves 34A: "Hungry hungry" game creatures (HIPPOS).
The first three theme clues were, I thought, quite good. 51A: Motivational words for a boss at layoff time? (READYAIMFIRE), didn't seem quite right. Or at least not as funny. The startling repetition of a word in the grid - SIR - is a nice addition to the military theme.
So it was a pretty good Wednesday, we were just stumped by the one square. DNF sounds so... I don't know, so bad. Let's call it a FWOE - "Finished With One Error." How's that?