When Iris kisses Eddie for the first time, she has a large gold ring on her right ring finger, then does not, depending on the distance of the shot.
Barry uses a pen belonging to an officer, to examine evidence at a crime scene. One doesn't use random objects to examine evidence, as it would risk contaminating the evidence. One also wouldn't examine something that's inside a wheel impression, at the scene, as it would risk destroying the evidence.
When Barry is first being tested for his speed, he starts running and the air pressure should have followed him thereby leaving a vacuum behind him thereby causing the researchers to pass out from a lack of oxygen.
It is stated that there were "energies" created in the event with the Particle Accelerator, among them anti-matter. Barry Allen states that those "are all theoretical," a statement that is not objected to by the scientists present; but, as anyone who knows particle science knows, anti-matter has been known to exist for a long time and has been produced in labs and are widely known to exist. They have not, however, been made by humans as of the airing of this episode.
Barry says that "the particle accelerator is light years ahead of what is made;" however, "light years" refers to a unit of distance not time. The phrase is a common idiom in English, and is not a goof.
The building the Arrow lands against (after his chat with Barry) flexes on impact.
After an oncoming car crashes and flips over, there is no one in the driver's seat.
During the initial flashback, a 2007 Chrysler Pacifica is seen, despite it being set 14 years prior to 2014, in 2000.
Cisco Ramon repeatedly uses the term "knots per hour" as a speed unit, which is wrong, because a knot (nautical mile per hour) is already a measure of speed.
Cisco Ramon tells Barry that the wind speed (of the tornado) is 200 mph and rising, and then says "If this keeps up it will become an F5 tornado." At 200 mph it is already an F5 tornado.
Cisco Ramon tells Barry Allen that the suit he designed should stand up to Barry moving "at high velocity speeds". But velocity already defines a speed - it's a "vector" which combines speed and direction.