Kyle Steyn collected the man-of-the-match performance while wearing a medical boot after going off with a foot injury, while Adam Hastings and George Horne both failed HIAs.
Smith said there was still a chance they could pass the necessary protocols to be in the selection mix for next Friday's trip to Cardiff.
"They failed the HIA1, so that is just a normal procedure," said Smith in The Scotsman. "They can still be available towards the end of next week depending on the outcome of the test that needs to be done from now on. So we'll see.
"They both looked fine to me, but obviously they failed the on-field or the first test that they had to do."
Glasgow skipper Steyn initially went off in the 52nd minute but but came back on minutes later when Horne was injured. Despite picking up the knock Steyn went over for his second try before going off again. Flanker Euan Ferrie took Steyn's place on the wing and scored the final try of the night.
"Kyle is a wonderful leader," said Smith. "We've got a very good relationship. He's just been going about his business in his own way. Silent but accurate. He's got his finger on the pulse across the team.
"To be rewarded tonight, the man of the match medal, there were a lot of other games where he should have got it but he didn't. So to get it tonight was important. He had to come back on. He got caught with what looks like a contact bruise on his shin. We're going to have to examine that and see what's happened. He scored a try with the leg like that. Hopefully, it's not that serious."
The challenge that caused Hastings' injury led to a red card for Benetton lock Scott Scrafton just before half-time.
"The red card did make a difference, I suppose, for them," said Smith. "But I still thought we had ascendancy the whole first half. Like last week against Ulster, we had ascendancy in every part of the game. When it was 14-0 up, I think we kicked it in the corner. When it was 21-10 up, we lost the ball in the lineout. There were moments where we could have taken the game away from them earlier without them being a red card down.
"I think we get spoiled in this competition with the quality of the rugby that's always being displayed. We asked for progression this week from last week (the narrow defeat to Ulster) and we saw that from an attacking perspective. We backed a good defensive performance from last week up with another good defence performance. We missed about six lineouts inside the 22, which is a work-on for us this week, but it's uncommon. So, it's something that we can fix."