You forgot to proofread
Before submitting your CV or application, comb through it for spelling and grammatical errors. While this may seem unimportant, having such mistakes will make you look sloppy and rushed.
You appear to have a bad attitude
It is easy for things to get lost in translation online. Sarcasm can go undetected, for example, because words on a screen are not as dynamic as live interactions. Therefore, it is important for you to make sure you come across as positive and professional at all times. Skip the humor and avoid sounding arrogant. Instead, opt to show your enthusiasm for the position and an eagerness to learn more.