I found that you can actually use some commands in replays.

E.g. when you use /spec xxx in SPR, you cause the replay to go OOS when there are more cars on track (you + AI). If there's only one player in race, it gets back to entry screen. You can also change laps, add penalties etc.

Or, in MPR, you can "ban" someone (it only shows the message).

Of course it’s not important to fix it, since it does not do any big harm, only OOS errors or nothing, but it's probably worth mentioning

which version are you using? in which version replays were recorded?
I'm just trying with B13 version, replays recorded in 0.6B, and cant get that.

Quote from DANIEL-CRO :

which version are you using? in which version replays were recorded?
I'm just trying with B13 version, replays recorded in 0.6B, and cant get that.

I forgot to mention that /spec command works in SPR only.

reproduced now

also other thing I noticed is that chatbox is not working if you are in single player and then press 1 to watch replay