At the beginning of the epsiode, the Professor is sitting on a table in the same room as Amy and Leela, seconds later he comes through the door from another room and the table is missing.
It's possible he left the room during the conversation between Kif/Amy and Zapp/Leela though, and possible someone (maybe Scruffy) moved the table during the minute or so the Professor was off screen.
When Kif starts getting sucked off into space, Amy grabs him by the face to try and save him. This should've theoretically gotten him pregnant, given how Kif was worried that Zap was the father due to him routinely using his toilet without Kif's knowledge, yet only Leela grabbing his hand counted.
When the crew return from the Nimbus, the angry dome is gone from the building. (Possibly the dome retracts into the building, or is detachable.)
The Maternifuge spins at 10,000 RPM. While Bender (and possibly Zoidberg) might survive the resultant g-force, the humans would be crushed.
The book Leela is reading gets much larger in size before she throws it at the screen.