At the end of the shooting sequence, both Jack and Gwen are shown shooting a hand gun from both hands at the same time. If you want to play some and use up extra ammo, then that would be sort of OK but it is not a technique taught anywhere as you have very little accuracy and the chances of hitting your target are very remote.
In the scene where Gwen is shown how to shoot, there is the sound effect of the empty cartridges being ejected from the semi-automatic pistols. This same sound effect is also heard when a revolver is used, which does not eject its cartridges as the shots are fired.
When Gwen is first shown in closeup as she chases Bernie through the arcade, the face of Burn Gorman's stuntman is clearly visible in the background.
As Owen tries to revive Edward, he thumps the chest rather than keeping his hands on it and pushing down in quick bursts. Not correct heart stimulation.
When Toshiko is first describing the information she found in Ed Morgan's medical records, she says he is claustrophobic, or afraid of enclosed spaces. This is at odds with his apparent unwillingness to leave his home. Later, when she is reading his medical records on screen, he is listed as being agoraphobic, or afraid of open spaces, a diagnosis much more consistent with his behavior.