The Saints released a statement on Wednesday confirming a file containing coaches-box audio had been uploaded to a league-wide shared folder last Saturday.
The file, which was meant to be a muted version of the behind-the-goals vision, was from St Kilda's 35-point pre-season win over Essendon last week.
It was available to download for several hours before the Saints realised their error and took it down.
It's unclear whether anyone accessed the audio before it was taken down.
If they did, they would have had access to the inner workings of Lyon and his coaching staff just weeks out from the start of the AFL season.
St Kilda chief executive Simon Lethlean said the club wouldn't be conducting a witch hunt over the error.
"I don't think the IT guys knew the audio was on and being attached (to the vision)," Lethlean told SEN.
"We haven't heard anything to suggest anyone has downloaded it. But Ross dealt with it with the playing group to let them know."
The Saints have since replaced the behind-the-goals vision with a muted version, which is standard protocol.
"This upload occurred through human error, which was corrected as soon as we were notified," St Kilda's acting football manager David Misson said in a statement.
"There is no certainty that this file has been accessed and downloaded by anybody, however, regardless of the low risk, we wanted to be on the front foot and proactive in our response.
"Our focus is on creating a program with high integrity, open communication and care for our people.
"As a matter of course, we addressed this issue directly with our playing group."
St Kilda's season starts on March 19 with an intriguing clash with Fremantle at Marvel Stadium.
Lyon was axed as Dockers coach at the tail-end of 2019 and rejoined St Kilda in October for a second stint at the helm.
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