There’s a steep learning curve for many interns and along the way, mistakes can — and do —happen. Most of the time, those errors are innocent and don’t amount to much more than a learning experience.

But sometimes intern gaffes can lead to major consequences.

We turned to question-and-answer site Quora to find out  the most catastrophic mistakes made by an intern at a company. Here’s what respondents reported.

The deal is off

Attention to detail can make or break deals. In a bid to secure a partnership with global shipping company UPS, a team had spent a year ironing out the details. “Everyone on the team had done backbreaking research, and the lead sales roles had spent several hundred hours crafting the higher levels of what this partnership would mean for both companies and drafting it into a beautiful partnership proposal (and I mean beautiful to read and to look at),” wrote Michael Shiplet.

“And then I FedExed it to them,” he wrote. FedEx, of course, is UPS’s main competitor to ship the package. “We lost the partnership two to three business days later.”

Grounding flights

London’s Heathrow Airport is among the busiest in the world. So imagine the chaos when a student intern eating lunch inadvertently brought flight traffic to a standstill.

“We were listening to the control tower instructions and timing how long the pilots took to respond,” wrote the anonymous respondent. “My colleague left for lunch … having turned his radio onto 'broadcast' by accident. As radio is one way, it meant that no one was able to send or receive messages on the frequency that was being used to give take off permission.”

“I started to eat my lunch to discover that all departures from the airport had been brought to a standstill by someone who sounded like they were eating their lunch,” the anonymous respondent wrote of the incident that occurred 18 years ago. “The realisation that it was the sound of MY lunch being eaten hit me about 10 minutes later. I rushed over and flicked the switch to off” and flights resumed.

Whine for wine

Every year at harvest, wineries hire interns to help in the cellar, according to Ashley DuBois, who explains that wineries have to process, ferment and barrel all of the wine they plan to make in a given year within a month or two.

So when an intern driving a forklift through the cellar bumped a tank holding thousands of litres of wine ready to bottle, the damage was irreparable.

“She got a little too close to the tank door and nudged the hinge just enough to dislodge it, busting the door open and creating a very powerful explosion of wine,” DuBois wrote. “This tank was on the upper level of a cellar, so wine didn't just flood that floor, but also the cellar floor beneath it. The pressure of the wine against the door [was] too strong for any combination of people to close it.”

Accidental poor taste

A picture says a 1,000 words but the message sent isn’t always the one intended. In France last year, an intern’s photo selection for an advertisement offering a free kindergarten service caused an uproar, notes Alexandre Coninx. “The problem is that the picture used as a background [in the advertisement] is Gregory Villemin, a 4 year old child that was murdered in 1984 and made the headlines of the national media for a long time (the murder was never elucidated),” Coninx wrote.

Sending the wrong message can be devastating to employers and employees alike. Gerald Salisbury tells of one intern getting two contradictory emails from the chief executive of his firm.

The first was a copy of an email “where the CEO was [complaining] to the supervisory board about the entire division and all the people and the high wages and that he was maybe going to shut the whole thing down in the future, he just was not sure when,” he wrote.

The second email, to be forwarded to all employees on Christmas day “extended his best wishes for all employees and Happy New Year and so on.” Inadvertently, the intern sent the first email out to everyone instead of second, Salisbury wrote.

A spy among you

Don’t underestimate the prowess of an intern — or forget to double check an intern’s background thoroughly, just like any other hire.

“We often hired interns, and we treated them as equals…We didn't send them out for coffee, we immersed them in the work and rewarded them when they contributed,” wrote Jay Bazzinotti, who worked at a company that he says helped propel the internet in the early days by inventing the error-correcting modem.

One, he recalls, stood out among the bunch. “He was quick and bright, and he provided real contributions to the technology,” Bazzinotti wrote. “Then one day, the FBI swarmed down on our company. They came in fast and hard and all work came to a stop while we wondered what the hell was going on. It turned out that our intern had stolen the source code for our most precious and valuable techniques and tried to sell them to the Chinese for the pitiable sum of $50,000. Unfortunately, the Chinese he was selling them to were undercover FBI agents.”  

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