In the scene where Howard, Rajnesh, and Sheldon are in the Mars Rover Control Room, the clock behind Howard can be shown to be jumping back and forth between different times, sometimes jumping backwards in time in later scenes.
When Leonard and Stephanie make out on the couch, Leonard's napkin disappears between shots and Stephanie's changes position. Although enough time passes between shots to rearrange the napkins, given the circumstances it's unlikely they would have taken the time.
When Leonard and Penny are speaking in the laundry room the detergent lid opens and closes between angles.
When Leonard and Stephanie start to make out, Stephanie's legs suddenly jump onto Leonard's lap between shots.
When discussing Howard's outfit, Sheldon refers to a "male peacock." All peacocks are male. The female version of the bird is a peahen. Sheldon would not have made that mistake.