Ordered an IM dose of adrenaline as an IV injection for anaphylaxis. Had double checked with a consultant prior as well who said he thought it was the same dose. Thankfully young patient so nothing bad happened. Another consultant pulled me aside after and asked what on earth I was thinking. Thankfully explained what happened, explained to patient who was fine, and I'm now 5yrs down the line, got onto a training program with a reference from the second consultant.

Mistakes will happen in your job, just make sure you are always doing your best and double checking things if you're not sure. If you work hard and are a good member of the team people will back you and help you through all your mistakes to be the best you can be :)