Joel,
I'm glad you asked this question and more glad that you are updating your distress signals. I hope others read this and check their supplies.
I'm a Coast Guard Auxiliary vessel safety examiner and the number one problem on boats examined is expired distress signals, second is life vests still in the package or stuck away where they cannot be accessed. Vessel safety checks are free, we do not issue tickets for failure to pass, we do not report boats in need of "things" to the coast guard or law enforcement. We simply issue a sticker showing you passed or do not issue that sticker if you need some items. I encourage every brat to have their vessel checked. David McKibben (Anna Leigh) and I (C-Cakes) are available to do checks at every CBGT and for those not in our area, contact your local CG Auxiliary and they will be happy to come and do a check.
And while we are talking safety, there is another important safety step we can all take: get a VHF with DSC (Digital Selective Calling) capability, get an MMSI number from boat US or the FCC, input that number to the radio. And, in the event you have an emergency, press and hold for 3-5 seconds, the emergency button on that radio. It will automatically transmit a Mayday message for you and will repeat that message until someone receives it and acknowledges your Mayday. Plus, if you have a DSC radio and someone else sends a DSC Mayday your radio will automatically receive that message and in some cases will display the latitude and longitude of the distressed vessel.
Boris, I agree that you have an approved day and night signal but I have to prick your bubble a little bit. In daylight putting the flag on your highest point, probably the VHF antenna is probably the best thing. In a mayday situation are you going to be comfortable leaving the helm and radio, climbing up to the radar arch, lowering the antenna, taping or clamping the flag to the antenna, raising the antenna back up, and hoping that someone will see it and then...the hard part...have a clue what that funny orange flag means? In the dark/fog the flashlight will indeed send a line of sight SOS signal, if the batteries have been maintained and the bulb is not broken. That's great if your potential rescuer is in the quadrant you are aiming the light towards and the light, probably at about six feet above the flat sea level is visible. And...to make that useful you have to do it continuously in a 360 degree swing, kind of hard to do that while at the helm, etc. etc. With all respect, meeting the technical minimum does not mean you have a really useful set of help signals that can potentially save your life or that of your loved ones.
Admittedly I am a little anal about caution and safety, (probably comes from having been a cop, an EMT, and a combat vet.

) but this is what I carry on C-Cakes: Cabin: 12GA flare gun with 6 flares, signal flag, three handheld flares, three handheld smoke signals, four lightsticks with 6ft string to twirl at night, Ditch bag:four lightsticks, flaregun with three flares, two handheld smoke signals, Life vests (mine and wife's): two handlaunch flares, lightstick.