Early on there's a scene showing Superman sitting at an old fashioned mechanical typewriter typing at super fast speed that only Superman would be able to do. Old style typewriters could not handle typing at speeds that fast without the keys getting all jammed up. The traditional QWERTY keyboard arrangement was invented specifically to keep normal non Super people from typing too fast.
As Jimmy and Tony are playing the tape back for Superman, the reels appear to be moving very fast, about 30 inches per second. This is very unlikely for a small, portable tape recorder.
It's stated the Tony's Diner is right next to the Daily Planet. When Superman gets the tip-off from Jimmy, he says he'll be there as soon as he can. Superman is then shown flying across the city to get to the Diner which is right next door.