I wouldn't assume hyperoxygenation is the same as hyperventilation. Linguistically they don't mean the same thing. Being hyperoxygenated means you're breathing in more oxygen than you need, or is good for you; being hyperventilated means you're being ventilated more frequently than you need, or is good for you. Hyperventilation doesn't necessarily increase the amount of oxygen actually in your bloodstream.
It's possible to be hyperoxygenated while breathing at a normal depth and rate.
Yes, oxygen can be toxic at higher-than-normal concentrations; the effects can vary and depend on the concentration and time of exposure.
It's not a concern to pre-hospital medical providers because oxygen is being administered to people who couldn't breath in enough oxygen on their own. Ideally it should be given only to people who need it (or request it); it's been my experience in training that on the street, oxygen isn't administered nearly as often as it should be according to the book and the teacher.
By the way, another term you may be interested in is hyperoxia. This is the condition in which a person becomes when that person gets hyperoxygenated. (This is just as hypoxia is the condition in which one becomes when one cannot inspire enough oxygen.)
Some symptoms of hyperoxia may include dizziness, nausea, twitching (especially on the face), and eventually convulsions. Lung damage, potentially irreversible, may also occur, as can damage to the retinas.