In The Flash #188, Wally single-handedly rebuilt the Van Buren Bridge between Keystone City, Kansas and Central City, Missouri. And he did so between the blinks of an eye. That even includes the time he needed to learn the necessary engineering skills to design the bridge. A very impressive feat, and one that made for a darn cool double splash page, if I remember correctly.
So here's my question: how did Wally move the materials? An awful lot of any bridge is made of large pieces of metal. Very large, and very heavy, pieces of metal. And Wally's power is speed, not strength. So how did he manage to transport and manipulate several-ton girders and supports?
And that reminds me of a little scientific complaint about something that I don't think I've seen since Waid's run: if two speedsters are running at a supersonic pace, they really ought not to be talking to one another. Or to anyone else, for that matter.
Similarly, if a speedster's moving over a short distance, other characters shouldn't simultaneously be talking all that much. Take JSA Classified #3:
The previous page showed Jay, Bones, and Mr. Terrific standing all of two dozen feet away from Psycho Pirate's location, and the next page shows Jay veering off right before he reaches him. Thus, Psycho Pirate manages to deliver about five seconds worth of dialogue in the time it takes Jay to move about twenty-five feet. Plus a second or two of Jay himself talking. Even I run faster than that.