Recently one of my paper was rejected because:
- The five figures were noted as Fig. 1, Fig. 2, Fig. 3, Fig.3 and Fig.4
- In the text I mentioned curve a), b) and c) in Fig. 1, but in the figure there are only two curves
- In the text I inferred that sample c) had a high degradation temperature than b), according to Fig. 5 (the fifth figure as the reviewer assumed), whereas in the figure, b) was obviously the highest of the three
- There were two curves in Fig. 2 but I mentioned one without the other
Due to one point of the conclusion which was inconsistent with the data (Fig. 5), and too many mistakes elsewhere, the editor directly rejected my paper (and maybe also checked the calendar once or twice whether it was Apr. 1).

Why? Because I attached the draft to the email mistakenly!
My supervisor had nothing to say about this.

Andrew,
Thank you for making me laugh out loud. Scientists are human, but what makes one more human is a touch of humility. The arrogant ones would never discuss such blunders.
I hope the editor in question was receptive to a resubmission – good luck.
Oh, I am so sorry. Hope you had a stiff drink that evening. Or morning. That is my worst nightmare, one that I have come close to living out. To be honest, it makes me feel better to hear that other people pull stuff like that as well. It’s not just me!
Sh*t happens. The good thing is, your paper was not rejected based on the scientific content, but dumb stuff that is easily fixed. Good luck with the second round!
I prematurely sent a draft email when applying for my current job (I’d meant to send it to myself to test whether I’d succesfully embedded a link). Amazingly they still interviewed me and it all worked out in the end!
These days I enter the “to” address as the very last item before sending.
@ Ennis: Yes, “to” the last – my newest sequelae.
I also make sure that I attach my files as soon as I’ve finished writing the words “I’ve attached…”. I’ve sent way too many messages that were missing their attachment.