Corrected entry: Several times throughout the show, notably in episode 12 of season 4, there is a wheelchair in the room with the MRI machine. MRI machines use very powerful magnets with strong magnetic fields: a chair with that much metal would almost certainly get sucked into the machine or at the very least pose a danger of getting sucked in and harming the patient. MRI machines are always kept on (it can costs thousands to turn them off and on), so it's not like they wheeled her in and then moved the chair before turning it on. You can watch a video of what happens when chairs get too close and how strong the magnets in these machines really are here: http://youtube.com/watch?v=4uzJPpC4Wuk.
Corrected entry: Chase, Foreman and Wilson wear ties almost all the time. Any doctor working with infecteous diseases knows that ties are huge bacteria herds and that doctors should absolutely not wear them. In fact, most hospitals forbid their doctors to wear ties. While some doctors may not know this, Chase, Foreman and Wilson work closely with House, who is an expert on the subject and would most definitely know about it.
Corrected entry: At the end of the Season 3 premiere, House breaks into Wilson's office and writes himself a prescription for Vicodin with Wilson's prescription pad. Vicodin is a Schedule III controlled substance, which means that a pharmacist requires verbal authorization from the prescribing doctor or his staff to dispense it to a patient, even another doctor, making the prescription useless to House, which he should know.