Hey, this is a weird bug I keep having, although the first time it cost me a goal. Sometimes I am just having outfield players...... become the goalie? You can see here on the screenshot my wingback is in the goalie garb (my goalie is the brown circle without a number in the midfield.
This has happened a few other times, and is well, frustrating.
Every time this comes up I do double check the tactics screen to make sure the players have not somehow switched around in there, but everything is fine there, and I have also seen that during the same highlight the goalie will "snap back" into wearing his kit/playing in goal again.