Commentaries:
This suggests that alcohol may have been the reason they did what they did. They may not have been drunk, but they may have been drinking. Remember, it was a time of great celebration. The Tabernacle had been erected, Aaron had been sanctified as High Priest, his sons were installed as priests, and the Levites had been set apart for their duties. Undoubtedly, a lot of celebrating was going on. The placement of these verses seems to indicate that Nadab and Abihu had been drinking. They were not thinking properly when they used common fire. Alcohol has a way of deluding a person into thinking that he is in control when he is not.
Perhaps all the other biblical references to drunkenness are nothing more than veiled references to this occasion. Someone under the influence of alcohol cannot serve God properly.
God describes the world as being drunk with the wine of Babylon's fornication. They are people who are in no condition to serve God because they cannot think straight spiritually. They think they are in control when they are not, so they cannot be holy. They attempt to serve Him in immorality and unethically.
John W. Ritenbaugh
Examples of Divine Justice
The influence of alcohol may have contributed to what Aaron's sons did. Perhaps they were not drunk, but had been drinking. Alcohol deludes one into thinking he is in control when he is not.
John W. Ritenbaugh
Presumption and Divine Justice (Part Two)
Other Forerunner Commentary entries containing Leviticus 10:10:
Mark 5:2
Luke 8:29