Rangers have been asked by the SPFL to explain how a controversial banner was allowed to be displayed before Sunday's Scottish Premiership draw with Celtic.
The tifo, which appeared to show an image of former Rangers manager Graeme Souness holding a gun.
The display was highlighted in the match delegate's report.
Rangers have also been asked to comment on missiles, including a glass bottle, that appeared to be thrown on to the pitch from the stand.
Shortly after the 1-1 draw, Rangers released a statement condemning the throwing of a bottle and say steps had been taken to identify the culprit.
The club also described the banner as "unacceptable".
Sunday's game was the first meeting of Rangers and Celtic at Ibrox to be attended by away fans since January 2023.
The bottle landed near Celtic goalkeeper Viljami Sinisalo during the second half, with Rangers substitute Neraysho Kasanwirjo - who had been warming up nearby - entering the pitch to remove it.
On Friday, Sinisalo said other items were directed towards him.
"First of all, I was hit with something in my lower leg," said the Finn. "It wasn't just a bottle, there was lighters, vapes, coins, mugs, all sorts.
"Let's say that glass bottle hits me or hits someone else, what happens next? What if it hits you in the eye and you can't play football after that.
"Those are the questions that we need answers for."
When Rangers and Celtic met at Ibrox in January, an object was thrown from the crowd and struck visiting midfielder Arne Engels, who required treatment.
"It's not the first time it's happened," added Sinisalo. "I was there when Arne was hit, [team-mate] Greg [Taylor] has been hit, [former Celtic keeper] Joe Hart's been hit, staff members have been hit.
"It's up to the authorities and the club there. I'm just glad I never got hit because things could be bad if you get hit."
Interim Rangers manager Barry Ferguson sympathised with Sinisalo, and said he had experienced a similar thing when playing in European earlier in the year.
He also voiced his hope that it would not cause fans not being allowed to attend derby matches in future.
"When bottles come on, that's something I don't like to see," he said. "It can harm a player.
"I've seen it in the past with lighters or what not. And I had that issue when I was in Fenerbahce when there was stuff flying past my head. It's not a nice feeling.
"You've got to be careful because the last thing we want to see is fans not being allowed because it's been far too long."